Since D4 announce I have this theory that D4 will make us choose our path. To help inarius, help Rathma or Help Lilith. Upon finishing storyline, you die and you reborn as a Demon, Angel or TrangOul revives you and endgame will be territorial war themed dungeons.
INB4 people freak out by the term MMO associated with Diablo4, please read
I really Hope Diablo4 is made into some kind of Cross-Breed between ARPG and MMo, should i say, stay a ARPG hack’n slash but borrow a MMO mechanic to empower its endgame Pretty sure that was the original plan for D3 by blizzard North
It could still be a full-on ARPG gameplay but with faction system for the endgame
Humanity VS Heaven VS Hell
storywise
Playing the storyline, you are face with choices that makes you choose between Lilith, Inarius or Rathma. Finishing the Storyline you are Reborn as an Angel or a Demon or get revived as nephalem(previously just a human) by Rathma. This would give good replayability to the storyline by having 3 paths, give cool looks to characters and create a justified neverending endgame
We have already seen convertions in the franchise, Izual an angel became a demon, Adria a human became a Demon, Tyrael an Angel became a human… pretty sure we will see Marius as a Demon is D4 too. And pretty sure that now that the gates of Heaven are closed and Imprerius is mad, they might perform tests to turn Nephalem into angels to garner their power
Gameplay use
Fight to gain control over towns and areas. The logic behind this could be like the existance of Harrogath. With Lilith’s uprising, world stone shard(giant ones) scattered all over Sanctuary are being the main target of Power Seekers. Fortresses are being built around them to protect them from falling into enemy camp
Having control of a WorldStone fortress could grant buffs to its faction members while doing quests in surrounding areas. Players could contribute to the fortress’s power by financing it with ressources, making the guarding monsters stronger, creating a natural ressource sink for the game. They could even defend it themself in special event
They already said they wanted to make it a Massive open world, this would take full benefit of it. There would obviously still be normal dungeon crawling, you could play the game without even caring about this mechanic. The only difference would be that Those fortress grant Shrine like buffs to allies on a certain radius on the map for when you farm and perform quests, its basically a Tug-o-war for faction buffs
Its still a traditional “Clear dungeons get loot” arpg, but its just a flavourful twist to it. It could also be a good pretext to have pvp ingame. The “Faction” system taken from MMOs is just there as a justification for the endgame repetitive grind, it turns the players into the “Eternal Conflict” mode
This theory is supported by Tyrael’s last speech in D3 “But within him beats a mortal heart, that will one day be tempted to corruption. On that day, will he have the strength to resist? Or will he be our doom?” Laying the groundwork for options
https://youtu.be/IBAKjviBElo?t=249