Darkshore is re-settled and restores connections between the kaldorei civilizations scattered through the reaches of Kalimdor, as is Ashenvale. A civilization built atop the tree boughs and into the trees itself, serving as a new capitol for the people of Darnassus. Fortifications erect to keep the kaldorei forces from marching into the Barrens and the Horde from pressing back into Ashenvale.
Lordaeron is still beyond any habitation. The Horde wins the conflict for the Arathi Highlands and restores connections between northern territories by settling Gilneas. With a functioning port, forces gain control of Hillsbrad Foothills, maintains the Arathi Highlands against future attacks and allows the Forsaken and the Blood Elves to function in their northern reaches of the Eastern Kingdoms.
Peace is brokered. Not out of good will, but because the war is beyond costly, neither side believes with any certainty they can win if they pushed the campaign and the death toll is so high that conscription is all but an inevitability, threatening to cause unrest and chaos at home. There is also the benefit of being able to trade with one another at in-between locations, offering mutual prosperity.
The prominent of the Horde oust Sylvanas. There is no violent coup, there is simply no need to with everyone who commands the Horde’s forces giving the order. They eject her from her seat. To kill her would lose the Forsaken’s loyalty- a useful asset in a collective of outcasts, and, after so many years together, might have more of a personal side to the Horde than when initially brokered, albeit cold. Varok Saurfang may be beyond crossed over her heinous actions, as would most of the world, but it is simply a balancing act that binds his hands from taking action on behalf of the Horde, while the outside world seethes in its inability to take due action, on the account of the war’s devastating expenses rendering them all but inoperable in all fronts beyond defending what is currently owned. The important part is that the Horde is back into the hands of those who make up the political power of the Horde and there is no further complaint. This does not wash her of her wrong-doings, there is plenty of room to chase political discourse to the tune of morally bankrupt decisions made in war, but this is for another place and another time.
The Night Elves become a focus of narrative in the Alliance storyline. They begin pursuing old ways of life and avoid the pitfalls that they snagged along the way, to reinvigorate a civilization once on the backfoot and usher it into an age of prosperity.
The Forsaken gain a considerable footnote in the Horde story. The long forgotten aspects of the Forsaken culture is reintroduced; individualism. The Forsaken express themselves in drastically different ways, some benign, some radical. More parties become involved in the future of the Forsaken, not just Sylvanas, whether or not she approves. The Royal Apothecary Society, the Desolate Council and the Royalists who fall in line behind Sylvanas all become entities and while their discourse is loud and considered barbaric to the outside world simply because of the different cultures that surround them, they all have the interest of the Forsaken’s continued survival, capable of meeting push with shove.
The Alliance and the Horde no longer interact with each other. There is far too much animosity to ever be quelled by anything other than a generation or two’s time. Unless it’s strictly professional and political, the two powers swiftly steer away from each other, under concerns that continued interaction could re-ignite some very tender hatreds, one that’d resume a war that is drenched with the fatigue of both sides.