This won't happen (Score 1)

The economy of motion of the mouse is going to be hard to beat. You can go anywhere on the screen by moving it less than an inch. It quickly becomes not just an extension of your body, but an extension of your mind. That's going to be incredibly hard to beat.

What will be interesting in UI development is to see what kinds of technologies can improve efficiency as additions to the mouse. Just as mouse+keyboard is more effective than mouse alone, are there interface methods that could add to mouse+keyboard to make the combination even more efficient? I have a hard time seeing how touchscreens or motion control would do that, but it's conceivable they could for certain uses. A touchscreen could be just the thing for photo editing, or video editing, if implemented properly.