The Void, like The Light, can grant visions that tend to be from a different perspective. Never false, but half-truths, and it’s up to those who witness them to discern what they mean.
For example, when Velen’s son was born… The Light showed him a vision of him holding an Eredar in his arms. It never told him the whole truth, and it was only after killing his own son that Velen understood what that vision meant.
We know that the Void showed Alleria visions of The Army of the Light encasing entire planets (and people) in crystalline glass. I imagine they’ve been doing what the Legion was trying to do, but instead of destroying nascent Titans, they’ve been preserving them forever. So there are worlds, and billions of innocent people out there, frozen in time.
Now the Void probably showed Alleria that to get her to turn against The Army of the Light. It had its own motivations, like The Light… But it wasn’t objectively false.
What if they realize we unwittingly freed an Old God on a planet already dying, and start pointing their freeze rays at us?
Then there’s also Bolvar who has been threatening to kill us every time we interact with him, that crown is taking its toll. Murozond and the Infinite Dragonflight. Whatever has been eating souls in The Shadowlands. Kael’Thas will probably come back again at some point, I’d put money on it. There’s infinite possibilities for whatever the hell that ritual Tyrande performed. A new, unknown, Titan facility detected on Azeroth that “MOTHER” hinted to.
There is a lot of plot points for Blizzard to keep WoW ticking on with.