I think this is likely the direction you'll see for a while, until procedural generation/MMO "tools" become cheap as fuck (we're getting there) and someone wows the genre as an indie. I hate to go back to the example, but almost the exact same thing happened with the 4X genre. You pretty much only had Civilization keeping the genre "alive" (parallels to WoW here) until a bunch of indie studios came along and revitalized it in a big way.
Yea. One of my old dreams designs for MMO would be the "single server non instanced MMO". Use next-gen procedural generation to create a continent with 50 times the size of current WoW, and like 8000 static dungeons. You use a GW2-style event system rather than an on-rail story-driven quest narrative: you are in a world of Adventurers, not Heroes. You're in for the loot and power, not to save the world. Factions galore, achievements everywhere.
Then, since you have that much estate, and people like to level, use the "I'm bored, let's make an alt" as a gameplay loop. At max level, you can open up the "Wheel of Fate" at any time, which lets you reroll to level 1, but with your old gear and a choice of different classes or races that unlock based on your progression. You start as human, but you played a lot in the north, in mountains and stuff? Then you can remort as a Northman (EQ barb). Or a Yeti (snow furry). Or an Ice Dwarf. And you've use more elemental spells than magic spells, so instead of a Sorcerer, you can be an Elementalist. Then, you can head to a different starter location and level all over again, but with an additional racial ability, better starting stats and a slightly better profession, and see new dungeons and stuff. That makes rerolling an alt part of the progression. Or, instead, you can stay max level for a few months, and go raid to get better gear (and better achievements, which unlock other classes).
The designers would focus on class designs rather than trying to make some "compelling story" or a new currency system. The hook is that you start as a basic Human Sorcerer, and work your way to Ancient Eldritch Lich Arcane Warlock Magus. If you want to. If you want to be an Empowered Ethereal Manifestation Void Elementalist Grandmaster instead, you might be (I hear those liches tend to be KOS to most factions). Expansions simply introduce more racial variants and class specializations.
But all of that DOES require a powerful procedural generation to make a compelling, yet shared world. Which means it's not quite there yet, I think.