For mine, and realising that I will both miss some things and seek to amend my design after reading others, I would want my camera to:
1. Only shoot RAW - I can't recall the last time I used a jpg straight out of the camera for photos destined for sharing. I may not do much to the photo but I will almost always make sure the whites are white and boost contrast a little. Therefore, I don't want all the jpg algorithms and menu options included.
2. 12 or so mp but high ISO - I don't print that big but want to be able to use the camera in lower light environments than the current D200 allows without the need for flash or other light.
3. Large rear screen that can be reviewed in all [realistic] light conditions.
4. Greater dynamic range - say 12 stops. I generally don't like the look of HDR.
5. Forgot about this one - full frame sensor - thanks Cameron

There is probably more but I can't think of it at the moment.
Knock yourselves out.