A lot. Not what they are going to do though, so this is pure speculation.
The things I would like to see: More sandbox play in a persistent world.
It seems that MMOs have moved away from this kind of immersion and into the idea that everyone must have a crack at every encounter that can spawn at all times. This leads to the kind of thing were you get those lame quests to kills X number of creatures in area and once you go there they are continually spawning - over and over again. So no removing them or stopping them from being there - they aren't going anywhere. That is such an immersion kill.
And because the world has to be ready to receive the next wave of heroes and his invites that means that the character (and hence the player) can't really have any significant impact on the world. So what is there to focus on instead? Usually it is power playing and character development. I get the geeking out factor of that and who doesn't like a good video game fight - but that is what it gets reduced to. Raiding with friends.
This main quest topic then becomes fight, fight, fight. No more TES quests like in the solo games such as solving a murder, resolving a dispute, using a skill like speechcraft to do more than get cheaper gear. No more reason to explore other than finding a new unique critter to give a possible kind drop of new stuff to fight with.
NPCs that matter and have any other kind of life than standing in one spot and either selling something or telling you what to do. Enemy NPCs that can detect you more than 10 feet in front of their eyes.
Real choices and consequences - though not the kind where you have to join a faction based on race.