During his fight in WoD, Kilrogg shows us the vision of our death.
Demons swarm over Undercity while Khadgar yells that the legion and Sargeras have won, and eventually we all die.
I know that since he is an AU Kilrogg, this might have not meant much. But I still wonder, why Undercity? And why the Legion? Was it simply to give us a preview of Legion? I think not since Undercity was not relevant at all during Legion.