To be honest - I do not think touch screen in an studio environment will be very common in the forseeable years. I can see there are some backdraws with that..
First (and for me most important), you do not have tactile feedback. Nothing works nicer that moving an slider by hand, while listening (sometimes even with closed eyes) to the minute changes you make. If you use an touch screen you have to rely on hand-eye coordination, what can be uncomfortable and distracting.
Secondly, most people use the monitor at an 90 degree angle (or even tilted forward) on their mix table. It is intensely uncomfortable to use touch in such an evironment. Constantly pointing forward and slightly (in my case) upwards will tire your arm very quickly.
Sure - you can replace you mix table by an flat (or slightly tilted upward) screen, but then you have problems with the first point I mentionned. On top of that, replacing an midi or other harware controler, by an big enough flatscreen is very pricy. Yes, there are mix consoles with build-in touch screen, but the pricing for that hardware is (in my opinion) far out of reach of small studio's (and I do not even dare to talk about home-enthousiasts).
Al in all, I should say there is in my opinion no pressing reason why Cubase should have an full-touch support in the short term. I think there is more important intercface (GUI) work to do, before submitting resources to develop named full-touch support.