Idea being that MMOs can survive and thrive with much smaller player bases these days and less traditional business models.
To some degree this is true now with story, raid focus, PVP focused, et cetera MMOs currently in the marketplace. By next year it seems we'll be seeing even more MMOs that are purposefully going for a niche audience.
With that in mind, I'd say the people for whom Secret World or Rift appeal to are quite happy with the endgame those games offer. Those are just 2 games I am personally familiar with and actively participate in for the sake example. Yet they might be two of the most satisfied player bases I have seen recently.
Whereas SWTOR [WoW theme park approach] was one of the most unpleasant, dissatisfied and angered player bases I experienced. It's still that way in TOR- I logged in last week...
So I don't think the "endgame" of games such as EQ/WoW is fading anytime soon. But do feel we are seeing a lot more variety & in turn satisfaction in what/where differing endgames are offered to player satisfaction.