I don't know what everyone else thinks, but after watching the Burden's of Shaohao series, with the in-game hints from Wrathion, I think the chances of us seeing a legion expansion are pretty high.
I wonder what they will call it?
As many, many people have pointed out in this thread, on the youtube videos, on reddit, etc... 'Rise of the Legion' makes literally no sense unless it focuses on telling the stories of how the legion originated when Sargeras first built his army. At this point in the story, it doesn't fit.
So what do you guys think, if it's a legion expansion, what will it be called?