Ok, maybe it's not the time to speculate, but here is my wishlist. Besides the obvious AF that I will not list, and the first point, these should be doable. And it would REALLY enhance my experience.
1. more silent shutter. Probably it's hard to get it as soft as an M9, but boy that would be sweet!
2. get an exposure lock in manual mode. Once you click it, you can adjust the aperture and the shutter speeds changes to match your chosen exposure. And it stays fixed until clicked again to release it. I like to shoot manual. But when I need to go from a portrait to a group shot, I now need to count the clicks in aperture and dial this in when changing the shutter speed. Just plain stupid, I think!
3. A histogram of the true RAW file, not of the embedded JPEG. The white balance trick trows me off for composition based on color. This should have been realized much sooner!
4. A metering that truly measures the raw output. I mean the meter when you look in the viewfinder. It should start blinking when there really is no information left. At this moment, I can get about 5 clicks further than the +2 and still have detail left in that spot. It would be MUCH easier to use spot metering with this feature and do a correct exposure to the right thing.
I think that apart from the first one, these improvements could be cheap to implement. Please!