Until Apple makes some changes to the OS to allow the iPad to function less like a large iPhone and more like a small Mac, I feel like most hardware improvements will be wasted. iOS doesn't even come close to utilizing the power of the current hardware, especially on the 12.9 inch model with its 4 GB of RAM. I'll probably be staying with my current 9.7" Pro for a while until they make the switch to OLED displays. I'd also like a pencil that is easier to store and perhaps a bit more geared toward writing rather than drawing. But it's not a huge deal to me. My only other requirement is that the iPad not get heavier. The 9.7" model is finally down to a weight where I can hold it comfortably in one hand for long periods.
Really though, it's the software and not the hardware that's holding the iPad back at this point.
Really though, it's the software and not the hardware that's holding the iPad back at this point.