I take delivery of a new phone/PDA, an HP iPAQ hw6915. I took care to choose a PDA that has a QWERTY keyboard; not all of them do. Ah, the wonderful QWERTY keyboard, like Dr. Watson, a fixed point in a changing world. People have been predicting its demise for decades, like they have been predicting the demise of newspapers. But it lives on, basically because it's a fundamentally good idea. My old PDA (a Handspring Treo) also had a keyboard (perhaps it still has; but it got stolen last week). Its predecessor, I think, did not. In the late 90's when everyone used Palm Pilot, one of the exciting new gimmicks was the "graffiti" method of text entry. But that idea doesn't seem to have lasted.
For keyboards to disappear, some good alternative would have to arise, and I can't guess what it would be. Speech to text translation is no good, since we don't always want to make a noise while entering our data, or let other people hear about the data. And there's ongoing work on recongising gestures/sign language, which may be useful for some people, but would probably not become mainstream.
(Added 24.1.08.) A useful thing I discovered recently is that when you are filling in an online form, you can use the tab key to jump from box to box. No longer do I have alternate between mouse and keyboard in order to fill in multiple boxes! Makes a good use of the tab key, whose original purpose is by now obsolete.