Originally Posted by
Shadowlands-is-fake
The war is the war of the North. Lots of different players that didn't learn from the Fourth War, and each seeking the power to rebuild and conquer the continent.
Which is why Gilneas and Quel'thalas won't be aggressors. They were there, and they've learned the lesson that rebuilding and peace is more important than war and dominance.
But the Scarlet Resurgence, a Stormwind with new leadership seeking power (nobility) and to purify with Light (Turalyon), a fragmented Forsaken people, the Amani, and a number of smaller factions like the Void and Infinite flight, could easily set the stage for a new war.
I'm not saying I want any of this btw. In my view, they should just revamp all of KA+EK and have us pick flowers in the sun while dealing with local Gnoll threats for two years.
But based on clues and rumours it kind of feels like things have been set up for a new conflict.
Edit:
Thinking about it further, it could also be that Quel'thalas remains Horde, and are the defenders. While the nobles of Stormwind may have sent their crusade to reclaim Lordaeron, for Turalyon it might be about taking the Sunwell and Quel'thalas in the end. After all, his wife won't stop talking about that. :P