There's really not a whole lot more that can be done to improve MMOs under current interface options. Improve the graphics? Sure. But then what once we're into hyper-realistic? Some of the things people are prone to ***** about like questing and its Kill X, Fetch Y, Go to Z, and Defend/Escort Q mechanics aren't going away, either.
There are really only two aspects left to grow upon, and one is going to be entirely subjective. That would be storytelling and user-generated content. Right now, role-playing the sense of improvising an alternate character and persona is generally frowned upon, largely because there are no tangible benefits to doing this well like loot or currency. Rules set by the devs themselves can also sometimes contradict how players might like to play, especially when it comes to things like hard-coded faction divides and/or class/race restrictions. I'm also one who believes that, while a given MMO may try to weave an epic plot involving the player as (one of) the main hero(es), how the worlds themselves tend to come and reflect this fails miserably.
So, as someone who used to RP on MUSHes 5-6 years before XI came out, I'm quite comfortable in the belief that the players themselves can drive a story if given the proper tools. Right now, being a villain in MMO tends to rarely stray far past being some form of PvP ganker. Not very riveting, really. But what if the proper actions could outright lead to a player/guild conquering a particular section of land and further manipulating it to their whim? More broadly, this translates to no two servers of a given game being exactly the same, but it also offers a potentially alternative goal to chase where instead of being a top raider or PvPer, you could be revered a lore-weaver. Naturally, plans and ideas would collide, but that's part of the fun.
But the above is the players simply affecting the known world. User-generated content, however, could be far more vast in its potential. Want to build an incredibly large labyrinth with traps and puzzles for people to figure out? You could. Want to make the digital vacation spot of your dreams that other players could come to for relaxation and more casual RP? Go for it. Feel like you could create the most badass war scene for players to try and fight through and survive? Should also be a thing. So, while some games may be toying with these ideas now, I'd still say they're largely in the juvenile stages of development. Even tribute things could be fun to experience, like if someone totally recreated the original Zelda overworld in 3D form.
Basically, our imaginations are where MMO evolution lie. It's just up to the devs to give us those user-friendly tool sets.
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