Based on how they've been messing around with endgame flow and making everything connected (gearing in particular), I'd say M+ will be cemented as a more viable alternative to raiding, probably maintaining the spike in individual responsibility. Mythic raiders who aren't actually in the WF race will still complain about being forced at gunpoint to grind out mythics in between raids by blizzard. I can't see WQs dying, seeing as that's one of the handful of features they haven't axed in the next Shadowlands expansion. They'll probably evolve along the way, though I can't really say how.