I suspect the next user interface revolution will be to use an AI camera to recognize your hand gesture movements to manipulate windows. And to recognize your facial gestures to pop up an interactive helper like Clippy.
The technology is there.
And why would you move your hands if you don't directly interact with objects, you could track your tongue touching or sliding along your teeth, best interface ever.
But then, what if you have a sudden gag reflex? Or a random epileptic seizure? And the AI thinks you want to do a format /f c:, or a rm -rf / command? Hmm.. the OS had better firewall off those special commands.
Use trash instead of rm -rf for example, it makes sure that files you remove land in your trash bin. Look this program up if you don't already use it, seriously.