the problem is CAD applications have a thousand commands, most of which are fairly common in usage.. quite possibly the genre of applications demanding the most variety in input than any other..
it also require numerical input (length/angles/etc) as well as text input (various notations etc)..
a CAD app on that thing would have to be entirely dumbed down in functionality in order to make much use of the limited input options.
we're not going to see advancements in CAD UI until we see us leaving 2 dimensional inputs/outputs.. we might see something different but nothing faster.. 2D i/o are all of the following -- pencils, touch screens, keyboards, trackpads, mice, lcd flat panels, dials.. etc.
you can only move X or Y in all of those.. multi faceted applications are going to require a third Z axis functionality in order to get the amount of controls necessary into seemingly simple interfaces.