Legion is awesome, but MMO has become a dirty term, for some reason. There is definitely player manipulation and "skinner box" stuff going on, but if you want to exist in a populated fantasy world there are worse places to go than Azeroth.
Runescape still has a popular following on twitch. Diablo and various "asian" MMOs come alive from time to time. A hardcore crowd keep PSO going in some form. "WoW 2" is not unthinkable.
I've never played the likes of Destiny, but I've often found it strange when people lose their shit at mechanics us WoW players have taken for granted for years.
Perhaps the thread necromancy is more appropriate than I give credit for, but I'm still enjoying my time in these online worlds. Add a VR element, and perhaps we will never leave...