I typed out a huge thing about this that is so far following along perfectly to what i predicted. But essentially Azeroth is gonna go and were going to be on a new planet while fighting off the void then take the fight to them.
I should say its more to it than that, I also talked about how its going to happen not just all at once but over a few expacs of story line. It all fit so far
hum…
did we ever see a planet void dominated or the Legion burned all of them?
N’Zoth is just gonna sit back and keep an eye on things.
Go to Disney Land?
If we kill him Azeroth will die … So we have to lock him again.
Sylvanas have the dagger … 
A void dominated planet can be seen from Telogrus Rift.
All the “Old Gods” are actually Azeroths nightmares come into being. (aka she has some funky taco bell before she went to bed). We can not defeat them without awakening her.
Run into the Main characters and get farmed like the little weakling he is for loot.