We had those laser-based mobile "virtual keyboards", but for something really interesting we'd have to improve the projection technolgy, i.e. full-fledged "holo

We had those laser-based mobile "virtual keyboards", but for something really interesting we'd have to improve the projection technolgy, i.e. full-fledged "holograms", which would apply for both the screen and the input device (if the quality is more "Leia"-like, then the physical screen will stay a while longer). I don't think we're there yet. But I fully expect to see Wiimote/Kinect-like 3D gesture technology to be incorporated into devices, probably soon after the devices themselves have a (pseudo-)3D display. Tablets already have front cameras, shouldn't be a big jump hardware-wise.