Less noise, much less, back to the 7/5d type thing. Less problems with reflections off the sensor, less problems with incedent light, basically turn the chip inside out so as the sensor is on the outside not the inside. Leave that mamal retiner behind put the receptors in the path of the incomming light not the wires.
An electronic blind (ie turning the sensor on and off), stuff all that moving mechanical stuff, it is out of date, not nearly as fast (1/300th flash sync, what is that doing still there), just put a switch in there somewhere.
I guess that would mean sony were first with a feature though.
Then a propper live view but still with the nice viewfinder. A new compression ratio for raw, even if it is lossless, to keep transfer rates up and file size down.