Cosmetically there are a few things to optimize. Resolution, of course, but to me this is not an urgent one - stable framerate is much more important to me. Next thing is better textures. Devs made a lot happen this gen to "fake" good textures and make games look awesome while the consoles where somewhat limited but they will look much better than now.
What I hope for are a lot more polygons for models as I hate to see blocky ones. But to me more open games are possible. Think of the broader view and details you get when you compare GTA:SA and GTA4 - next gen will hopefully have the same huge leap. A combination of all, meaning better overall graphics, better models, better textures, wider view. Skyrim actually is a big game in itself but this means "hard" size. It is more a question of "what is rendered to my screen" and how much detail it has, not how big the world is that devs put on the optical disc.
