+ Glove (or rings, or paint-onto-nails chips, for Pete's sake) motion sensors to sense hand, finger movement. Chording input, gesture interpretation, whatever you want. No more need for a keyboard and the real estate it demands.
The motion sensors are already ubiquitous. This is just a new form factor, plus probably wireless communication à la Bluetooth or similar.
+ Heads up in glasses (or contact lenses, or whatever) display. Again, eliminates the need for the real estate, and power consumption, of a traditional display. A side (or additional primary, to those who worry about these things) benefit is the recovery of privacy; shoulder surfing becomes much more difficult if not impossible, depending upon design.
+ Audio: Well, that's already solved as well. Just a matter of what you plug the earbuds into (wire-fully or wirelessly).
Goggles will also aid 3D display.
All of these elements are coming along nicely. All that's needed is for someone to put them together in an appropriate form factor.