For me I want to be able to play the way I want. I want to still be able to play as a conjurer not just another generic mage.
This.
I doubt it will happen, but I would absolutely love to see a character system like Star Wars Galaxies of old, where you could invest in whatever skills you wanted, however you were limited in what you could pursue to preserve balance.
...Actually, sounds a lot like Skyrim...
I also want to make sure it is completely open world, and not a "Warhammer: Online" or "Star Wars: The Old Republic" version of linear world.