I'm calling it now.
We're likely to see X'era, Argus, Kil'jaedan, and possibly at least one of our old god buddies in Shadowlands, since lore states they are well and truly dead...
...which means they are probably hanging out in shadowlands bitching about Azerothians (And to some extent Argussians because Draenei, LFD, and Draenorians because orcs)
So, who's ready to speculate about a patch or two being dedicated to some of those who we thought we were rid of?