RTS games would benefit from a touch screen, obviously, but beyond that...
FPS games would still be better on PCs thanks to mouse/keyboards, Third Person platformers/shooters would function almost identically, Driving games would also be pretty much the same...
Other genres could use the touch-screen, I guess.
There's adventure games, which would pretty much not use the TV and therefore defeat the purpose of being on a console, but would control rather well.
Sports games could use the touch screen to enact strategies and tactics - say, use it as a map in a Football game to plan out your team's defence.
Indie games could really use the touch-screen in innovate ways, but then they always innovate so we won't count them.
RPGs could use the touch-screen for menus and inventory management to avoid cluttering up the big picture on your TV, or possibly planning combat a bit better.
There's possibilities, but it's tricky to see them being major game-changers or really revolutionizing genres.