If it is just support for preemption and an MMU MS already created an API for that, it is called "DirectX 11.2" or more properly the WDDM 1.3. 11.1 (WDDM 1.2) supported full preemption, 11.2 supports page based virtual memory.
I dunno, I guess we'll see how performance in real games actually shakes out but if this is nothing more than an API with a couple newish features, features that DX already supports, I'm not really sure that the "giveashit" factor for devs will be very high.
I also wonder as to how they'll handle GPU memory mapping in user space. With large memory cards, that is going to mean saying no 32-bit versions which at this point is still something that may be problematic for game developers.