I think the computer, the telephone, the PDA and the web browser will...
* First, converge into a single device: ** a portable handheld unit like an IPaq with a wificard but more powerful)
* Then the devices will get smaller and begin incorporating text to speech interfaces ** And a cellular phone headset will sit in your ear while the computer itself sits in your pocket or rides on your belt. ** You'll take the device (or some display device) out of your pocket only when you need to see a visual display. In general, you'll interact with the system (and the network, and your friends) through speech.
* Then, the headset and the visual will be incorporated into a HeadsupDisplay built into the frames of your glasses. ** (The relatively heavy computer will still be on your belt). ** These will become popular e-book devices (with wireless access to all extant literature, and custom text-to speech interfaces that read to you while you drive) and so they will acquire a quaint high-tech name: ReadingGlasses. ** Popular options for geriatric babyboomers will include the *** a digital magnifying camera *** high volume ear-pieces for the hearing-impaired. (I like to think ReadingGlass options will be mature and cheap by the time my vision, hearing, and manual dexterity begin to fail. I suspect ReadingGlasses will probably be a relatively long-lasting plateau during which the heavy computer unit will get smaller and smaller through miniaturization, and by "borrowing" computation from nearby computers.)
* And then the device will start being internalized, drawing power from the body's mechanical and chemical energy affordances. (Don't freak out: we've already internalized dentures, pacemakers, artificial hips, and artificial hearts. These are life-extension and quality-of-life-extension technologies.) ** (The back to nature freaks in particular will like these units, because they will be able to hike contemplatively through the woods "hearing" Thoreau's Walden read aloud while they walk hands free and their heads up.)