Agreed. I don't think it's going to be happening in the next 20 years, at least not well enough to replace the keyboard. However, it's the only alternative I can imagine that would be a real improvement over keyboard input.

Edit: Note, I can imagine the need for direct text input being reduced over the next 20 years thanks to UI changes ("Select your house on this map" replacing "Type your address in this box", for example), but I don't think that the keyboard will go away as the main tool for doing it when it is needed.