I think one thing that will be great for the next generation will be physical world interaction and new gameplay possibilities. Physics, fluids and AI could completely open up the next generation for great gameplay possibilities. That's the biggest gain in my opinion. Games like Hydrophobia will suddenly become more feasible.
This current generation of consoles just don't allow you to have everything physical and separate as you will swiftly find yourself merging objects and removing destructibility to gain draw calls so you can compete with others visuals.
Rendering techniques will slowly but surely evolve as everyone moves to running a realtime rendering solution (most people are running it already). I'm sure in one years time if you was to compare now and then you would see a drastic difference. Its simply the tip of the iceberg. The stuff I see on a day to day basis changes everything, the next generation is going to be spectacular, even if the hardware isn't what we had hopes it would be. With a will their is a way