Not comparing tablets running Windows RT with attachable keyboards, I’m talking about a pure laptop/ultrabook with the difference of having a touch screen. Focusing on the windows 8 OS which is built specifically to be “touch friendly”, I have not found any real major benefit of having a touch screen.
Much of my reason for feeling that the touch screen is a gimmick is that it poses next to no use in the desktop mode of windows 8 (AKA the vanilla windows interface, not metro). The icons are small and fiddly to press, closing windows require delicate and precise presses on that increasingly frustrating small close icon.
The next possible evolutions to the user interface section of consumer devices are far and wide, reaching deep into the unknowns. The closest materialization to the “next big thing”, personally, I would have to guess to be precise motion sensing devices that work in tandem with screens. Imagine the Xbox Kinect, Playstation Move or the ASUS Xtion.