The thing about WOW and Blizzard is that if something causes their game to start failing, They will change it. Be it graphics, balance, or gameplay, they'll at least work on changing it enough to keep people from leaving. Other games abandon their work after a few years, Starcraft had a patch 11 years after it's release, Diablo 2 had a patch 9 years after release and expects another this year. I can't think of another free to play online game with that kind of dedication. It should be even stronger for a game that's taking peoples money every month.
I guess I can throw some things out there I think would be cool in a game if they could ever be done right.
I want soft level caps. Cap the quest XP at 50, raid quest up to 55 and when you get there the XP per level just skyrockets where only a few HARDCORE people are able to get 60 before the expansion hits and gives quest XP to 55 and raid quest XP to 60 and hardcores being able to grind to 65 or so..
I want to see HUGE procedurally generated worlds, items, creatures mixed with innovative story telling and questing and graphics. Procedurally generated "good" graphics? haha...
Ever-changing landscapes and stories. Procedural generation could do this. Raid a town, Do you take it over and take a % of the income or just burn it down? I want to see a lot of Megaton(fallout3) like changes in an MMO, preferably with even more of an impact to the game than that decision which I shall not spoil.
I'm not saying it should be an easy task to make big changes such as moving or taking over a town. I just think it should be possible.
Things that my next MMO MUST have is a solid, user friendly, responsive user interface. WoW has a great UI and it's made better by tons of addons to make any flaws easier to deal with.
The next MMO I play needs to have good animation and camera. I just cannot play a game with flawed animation or camera for very long especially 1000s of hours. Character movement animation is the most important. A character that "floats" because his run animation and actual movement speed aren't synced is one of the most annoying things for me. I can't enjoy a lot of games to the fullest because of horrible 3rd person character animation. Oblivion, Fallout3, Everquest, SWG, COH all had crappy PC animations. I forgive FO3 because it could be played as an FPS but Melee SUCKS in first person and that hurt Oblivion for me but I only managed 110 hours in that game. WOW did animations right. Characters stuck to the ground, laggy people didn't blink across your screen, Animations flowed together well enough. TOR looks good in this department mostly, The strafing and full speed walking backwards sucks but It's not nearly as bad as some games. I'm not a big fan of the free camera either. I like my auto adjusting smart camera from WOW more than anything.
Damn, That last paragraph is too hard to read. I was just gonna delete or re-write it but meh, I'm lazy. If you can decipher it, GG. If not, NP!