Maybe later on when the prices come down Nintendo will come up with a uMote+ which will have an HD 3D screen. Right now though, I think their priority is to try to keep the WiiU SKU (which will include a uMote) as affordably priced as possible while still being able to at least break even on it.
Oh yeah, and one other thing is to beam out an HD/3D display to the tablet is much more taxing on the WiiU hardware. So for that reason it probably will never happen. You'd probably have to wait until the 9th generation 7 years from now or something, when Nintendo will come out with the "Super WiiU" which will be 5-6 times as powerful as the WiiU. Of course, by then holographic stuff as seen on Star Trek might be on the horizon, so HD/3D will probably seem obsolete.