Realistically? Considering the political weight of some factions, the pants-on-head levels of stupidity of others, financial burdens, social and religious differences and the like, I’d be more in the mindset of factions breaking apart and forming into new ones without losing the Alliance and Horde, respectively.
Let’s go … lets say we’ll do 5 years after the start of WoW, so we put ourselves in the middle of the Cataclysm, the most politically stressful time in WoW with the Twilight Hammer tearing the Horde and Alliance up from within, massive droughts, food shortages, civil unrest and internal disputes unseen since.
Alliance:
Stormwind-
Between abandonment, heavy taxation, forcible conscription and active starvation, Westfall and Duskwood have gone into open revolt and sided with the Defias, leaving Stormwind with Elwynn Forest and the financial money-pit that is Redridge as their only confirmed territories. While Westfall has not been producing much in the way of food and Duskwood has been a non-performer for years, the loss of territory, and taxes, stings more than the Council of Nobles would like to admit and Varian’s refusal to enact a more militant reclamation of their lost territory causes political strain as the High King is more focused on, you know, saving the world and the Council is wondering if they can go 2-for-2 with monarchs and rocks …
Westfall and Duskwood form their own faction, the Defiants, and with their mercenary connections to the Goblin Cartels, are able to trade lumber and ore for food. Stormwind, already struggling with civil unrest and large swathes of the population defecting to join the Twilight Hammer, now has to deal with more of their disaffected population fleeing to Westfall to escape conscription and taxation, leading to even more shortages and crippling their military supply-lines.
Ironforge-
While still dealing with the Twilight Hammer cult infiltrating them, the loss of their best farmlands in Khaz Modan, the arrival of the Dark Irons and the eventual ‘union’ between the three Clans of Dwarves sends shockwaves deep inside the Bronzebeard and Wildhammer Clans. Just as there are Dark Irons who refuse to accept peace, there are Bronzebeard and Wildhammer Dwarves who refuse to acknowledge the Council of Three Hammers and split off, forming a new Clan composed equally of Bronzebeard and Wildhammer, the Goldfeathers, and move themselves to Kalimdor, settling into the Southern Barrens and, once there, forcing the Horde out of Bael Modan and rallying the surviving Theramore refugees under their banner. With a combination of Wildhammer Gryphon-riders maintaining aerial superiority, and Bronzebeard tanks and Titan artifact specialists, Bael Modan remains a tough nut to crack and the Quillboar quickly learn to never bother a Dwarven convoy down to the flooded Thousand Needles for seafood and salvage, or for lumber in the Dustwallow Marsh.
Gnomeragon-
Heartily sick of being ignored by their ‘allies’ and with their capital still irradiated and infested despite years of Alliance adventurers picking over the scraps, the Gnomes are still technically a ‘part’ of the Alliance, but only on paper. With no payment for their assistance, no aid to recover their home, no respect for their continuous support to their allies and their tenuous place within Ironforge now barely there with the squabbling between the three Dwarven Clans and their political nightmare, the Gnomes pull as many of their people as they safely can out of the Alliance and start rebuilding a new capital in … the mountains of south-eastern Badlands, counting on the inhospitable terrain, the lack of easily available resources and their ingenious inventions to keep others away, and quickly create a new capital, relying on the local geothermal situation to power their city, turning salt-water into fresh water to feed their hydroponics farms and launching periodic raids on Uldaman and Angor Fortress to recover resources and Titanic technology to expand their options.
Teldrassil-
Tyrande and Malfurion’s decision to invite the Highborn back into their society and to train new Mages is the straw that breaks the camel’s back. Between Staghelm’s betrayals, Maiev being a salty little crotch-weasel even after 10,000 years, and the growing unease about their place in the world and how little their joining the Alliance has actually aided the Kaldorei, a sizeable chunk of the Kaldorei just up sticks and leave rather than face the Horde again, having come to believe, with some prodding from both the Twilight Hammer cult and their own misgivings about the angriest High Priestess in living memory and their narcoleptic Arch-Druid, that Elune has turned her face away from their people due to the choices that have been made, and this splinter-group, the Silverwing Devotees, take themselves off to Feralas and officially cut themselves off from everyone, the Alliance and the Kaldorei included, and devote themselves entirely to Druidism and worshipping Elune, adopting a KoS to any spellcasters outside of their own people and using magically dominated animals and spirits to make up for their limited numbers. While this loss does weaken the Kaldorei, they do still manage to hold on to what they do in the main timeline, but this loss of people due to a lack of faith in them rattles both Tyrande and Malfurion and causes certain changes to how they interact with others …
Gilneas-
Crowley and Greymane cannot reconcile as Greymane continues to refuse to accept any responsibility for what’s happened, and Crowley is consumed with rage and grief for his long stint in prison for refusing to abandon the Alliance. Ironically, as the Kaldorei recruit the Gilneans and then there’s the slow connection between Varian and Genn, Crowley comes to the realisation that the Gilnean people will never be free of Genn’s self-centered leadership, and rallying those Worgen and Gilneans who blame the Greymane royal family for the loss of their kingdom, their humanity, and their new position in the Alliance as beggars at the table, leave both the Gilnean Kingdom-in-Exile and the Alliance and move to, of all places, the Scarlet Enclave in the Eastern Kingdoms. With Archerus no longer involved with the Scourge and most of Crowley’s new mini-kingdom either immune or resistant to the Plague of Undeath, and the Scarlets long since abandoning the area, the ‘Kingdom of Crows’ settles in and tries to rebuild, fortifying the entrance to the Enclave and working alongside the remaining Argent Dawn/Argent Crusade membership in the region.
Exodar-
Velen becomes increasingly disturbed at how easily he’s brushed aside by the other leaders of the Alliance and how unstable Varian has become, and takes comfort in Anduin’s bright mind and gentle heart, and actively takes steps now to deal with the horde (heh) of refugees from the Human territories who came to him seeking guidance and prophecy, leading to a much more aggressive restoration of the islands around the Exodar and the exposure of the Legion’s active hand in Fel-blighting the region. While the Draenei and their new recruits aren’t able to fully cleanse their new homeland, they do manage to cleanse Azuremyst Island and the south-eastern half of Bloodmyst Isle, pushing the Satyr, corrupted beasts and the Legion into the north-western half. With farmlands, the beginning of a new city and fraying bonds with the Alliance, the Draenei double down on being a voice of peace in the chaos, and even make inroads with the Sin’dorei and the Factions within the Horde who likewise see the road they are all walking down as self-destructive …
Horde:
Orgrimmar-
Garrosh is certainly quick to appeal to the Orcs … but just as many are unnerved by his disdain for the other races, who have been at their side for far longer than some Johnny-come-lately from Outland. His exiling of the Darkspear Trolls from Orgrimmar, even before Vol’jin makes a threat to the Acting Warchief, further causes concern and a groundroots ‘objection’ starts to spread out from Orgrimmar, finding fertile ground in Razor Hill, the Den and the Barrens. Since the Orcs cannot disobey a direct command, they follow the wording of the orders, not the spirit. Prisoners ‘escape’, supplies ear-marked for the front-lines and ‘liberated’ from the civilian population are reported as rotten or not fit for consumption and somehow find their way back into the hands of the civilians, soldiers conveniently ‘forget’ when they see thieves making off with supplies to feed their families, the list goes on and on.
As Garrosh starts hammering home he will only ever acknowledge strength and military acumen, this ‘objection’ flourishes into outright belligerence. While the Orcs cannot actively rebel as their Acting Warchief would openly slaughter them, and with the Twilight Hammer running around, the Kaldorei ready to kill anybody who goes north or west into Stonetalon or Ashenvale, and access to the south of Kalimdor cut off by the Great Divide in the Barrens and the roiling conflict with the Penal Legions of Stormwind, there’s nowhere for the Orcs to go. This results in what becomes known as the Scorpid Rebellion, the Orcs and their allies who object to the Warchief’s needless brutality and disdain for the other races within the Horde to take the Scorpid, resilient, relentless and too many to ever truly crush, as their symbol, doing what they can to express their displeasure and disrespect from ‘underfoot’, ensuring that the Warchief’s dreams of conquering the world for a ‘pure’ Horde remain just that.
Echo Isles-
Exiled, insulted and with Orc blades at their neck and back, the Darkspear are reeling and angry. All their loyalty, all their efforts, spat on by this strange Orc from Outland who disdains all that they’ve done for the Horde, and the Orcs. But they can’t just leave the Horde, can they?
Despite Vol’jin claiming that the Darkspear can fight for the Horde from within, many are heartsick from losing everything only to be spat on. From their ancestral home in Stranglethorn to Zalazane’s betrayal, it has been a thorny and winding path for far too long, and when the Zandalari call for the Trolls to unite to rebuild the Twin Empires … a sizeable chunk of Darkspear throw in with Zul’s efforts, siding with the Prophet out of a growing concept that no matter how loyal they are, no matter how hard they fight, no matter what bonds are made, they will always come second to the Orcs in the Horde. Darkspear Defectors, known as Zul’jin’s Ghost, do not go to Stranglethorn, but rather Amani territory to assist the Forest Trolls there, using their knowledge of Sin’dorei tactics and magic to aid their new ‘friends’, but are mistreated badly for being ‘weak’ and ‘jumping from ally to ally, like a flea’, and are likewise targeted by the Sin’dorei as traitors, drawing the ire of the Blood Elves onto the Darkspear as a whole even as Vol’jin and Lor’themar both work to point out these Darkspear abandoned the Horde and betrayed Vol’jin.
Despite these set-backs, Vol’jin’s dismantling of the Zandalari plot and his politics earn the Darkspear as much respect as they lost to the defectors, and bring other anti-Garrosh factions within the Horde under his loose ‘control’, such as it is, meaning that going forwards, Vol’jin knows he does not stand alone against the Son of Grom …
Thunder Bluff-
Concerned at the rising bloodlust under Garrosh, worried at the elemental chaos and the disruption of the spirits and with the Alliance gnawing at their borders, the Tauren struggle to keep their footing as the spiritual heart of the Horde, and when Cairne inevitably challenges Garrosh to Mak’Gorra after mistakenly believing that Garrosh was indeed behind the assassination of a peaceful meeting between Kaldorei and Tauren Druids, and Magotha makes her play for power, a tipping point is reached.
Despite all the bonds between them, the Taura’he people realise that the Horde might be unsalvageable under Garrosh, and while Baine does manage to exile most of the Grimtotem and swears the Tauren to the Horde again, a number of prominent individuals claim they will have no part in the bloodshed to come, that the Acting Warchief is a traitor to everything that Thrall’s Horde stood for, and leave the Horde.
While the supporters of the Warchief howl cowardice and treason, the Tauren know the secret paths of Kalimdor like the back of their hand, and end up becoming the backbone of the slow rebellion against the Warchief, passing messages and creating supply caches for the rebels to use, as well as undermining Garrosh’s efforts in the Stonetalon Mountains, Feralas and the Barrens, while many Orcs are further left agonizing over their loyalty to the Horde, and its acting Warchief, if the Tauren, the spiritual heart of their Horde, would leave rather than try to turn the Horde’s course of action to nobler ends.
Undercity-
No stranger to treacherous politics and needing support herself, Sylvanas quietly watches as the Horde roils and tears itself apart under Garrosh, her loyalist forces currently occupied with a quiet rebellion of her own.
With the Lich King dead, the Forsaken found themselves without purpose, and Garrosh’s invasion of Gilneas had shocking fatalities amongst her people, but worst still, her Val’kyr had a mixed reaction amongst her Forsaken. While most of them were delighted to know the Val’kyr could revive a Forsaken in nearly any state, raising the dead caused a schism as many Forsaken saw their current state as a horrific curse, and no matter how dire their relationship with the living was, doing the same to another soul, even if ‘free will’ was involved, was a step too far.
Some saw this as the continuation of their ‘race’, a necessary step to ensure the Forsaken did not disappear from the world. Others saw it as a betrayal of their very purpose, to end the Lich King and all the Scourge who ravaged their kingdom and defiled so many of the living with the Plague of Undeath. While there is no outright revolution or open conflict, a sizeable chunk of the Forsaken used that same ‘Free Will’ argument to pick up sticks and go join the Argent Crusade in the Plaguelands, preferring to use their remaining time and skills to try and restore the land to some kind of liveable state and to erase the Plague.
Her forces are nowhere near as numerous as Sylvanas needs them to be, and the loss of so many skilled veterans has left the Forsaken short-handed, which in turn draws the ire of the Acting Warchief and makes the Banshee Queen consider less palatable options to preserve her Unlife from the ‘Abyss’ she saw after her attempted ‘early retirement’ atop Icecrown Citadel, including recruiting the San’layn earlier than in the Main Timeline, as well as ‘forcibly’ recruiting Liches and Death Knights from Northrend to use them to add to her forces as discreetly as she can.
The hidden complexes beneath the Undercity thrum with Unlife and horrific experiments, but a new Plague of Undeath is created, one that is far more discreet, shows far less physical symptoms, and leaves the mind open to ‘suggestion’ in the final stages of the infection. The latter half of the ‘2nd Generation’ of Forsaken are thus much more pliable, with the occasional ‘Dumas’ raised being a simple ‘quirk’ in the system, and while Sylvanas struggles to uphold the orders given to her by Garrosh, with every corpse she claims, a new army of loyal troops, arrows in her quiver, shields against the Abyss, grows with alarming speed.
Bilgewater Harbor-
Treachery and conflict isn’t exactly unknown to Goblins, but the state of the Horde certainly riles up the former slaves of Gallywix, with many Goblins considering tearing up their contracts and going rogue, even if it does mean ending up afoul of Goblin Law and the Horde, but certain Goblins, including Midna the Tall and Gazlowe, convince them to stay the course but be ‘smart’ about it.
The Goblins have no love for the Alliance under the best of conditions, let alone after their ship was blown to scrap and the SI:7 agents were willing to kill them all, but they’ve also little patience for the Horde that’s struggling to pick a side in the middle of a global cataclysm, pun not intended. But Goblins do align with a winner, and Gallywix is despised, even if he cannot be deposed outright. The contempt both Garrosh and Gallywix have for each other is also on clear display, and a canny Goblin makes a play for not just power, but control. Midna the Tall rallies many of the disaffected under her banner to form a new Cartel, also aligned with the Horde, and pitches her deal to the Acting Warchief with a very simple hook.
“I’ll deal straight with you, no hidden clauses, no runaway costs, no ‘unforeseen’ blowouts. Back my claim to Trade Prince, keep my people safe from Gallywix’s Gob Squad and knee-breakers, and I’ll build your war machines without trying to squeeze you for every gold coin you’ve got.”
Garrosh applauds her ‘moxy’ and grants her wish, but rides Midna and her people hard, for when Gallywix learned that there was going to be a rally against him, he pulled all his wealth and most loyal goons into his Pleasure Palace … just as intended, while Midna and the Blackfuse Cartel took Bilgewater Harbor and all its industry for themselves, leaving Gallywix nothing to barter with but the gold he lusted for so much.
The political and mercantile ‘dueling’ between the Bilgewater and Blackfuse Cartels within the Horde never reached open conflict, but the push to see whose machines were better, whose profit margins could be greater, and whose efforts could better ingrain themselves to the Horde pushed the Goblins further than they ever did in the Main Timeline, much to the amusement of Garrosh who profited either way, no matter who came out on top.
Silvermoon City-
Between a growing horror that they were on the wrong side of history again, the Acting Warchief’s contempt and belligerence pushing the Sin’dorei away from the Horde, the Zandalari Uprising bringing Darkspear rebels against their rangers and blood knights, Lor’themar is hard-pressed to come up with reasons why the Sin’dorei should remain with the Horde other than ‘They will kill us all if we try to leave’, but with Sylvanas consumed with her own rebellion and now openly using Necromancy to raise the dead for her ‘2nd Generation’ of Forsaken and the Alliance roiling with debt, revolution and whole swathes of the population fleeing to join the Twilight Hammer Cult, there’s no real options for the Sin’dorei on the table.
There’s no guarantee that Garrosh won’t try to kill them all if they leave. They cannot guarantee that the Alliance will accept them after the madness of Kael’thas and their joining the Horde to survive, especially since the Alliance sent envoys to the Sin’dorei back in the Burning Crusade whose sole objective was to destabilize the Prince’s efforts to stop all Sin’dorei from withering, and the Kaldorei have never been shy about the fact that they would kill the Sin’dorei on sight the moment they felt they had justification for it, let alone their military presence around the Sin’dorei capital that saw many civilians and military personnel slaughtered.
With his hands tied, Lor’themar subtly aids the growing rebellion against the Acting Warchief while publicly doing what he can to placate Garrosh with shows of military aid, but in secret, Lor’themar sends out agents to try and find the resources to rebuild the mystical barriers that once surrounded the lands of the High Elves, planning to, if things turn truly south, rebuild the Runestones and shroud the ever-golden forests in mystical mists, to entrap an army and allow it to be whittled down by the Sin’dorei’s smaller forces, and to obscure his next move …
If nobody minds, I’ll do then 10 years and ‘current’ version later, my brain is swiss cheese right now.