Android based open-source firmware/software with open plug-in framework.
We really need cameras that run Android instead of proprietary "closed" software systems. Then we could use all the existing Android apps to take photos, and we could also getting much better control of the hardware with open source apps yet to be written, instead of depending on the imaginations of the camera vendor companies. For example, software that would automate time lapse photos, do HDR and other editing in camera, and many other functions that we cannot even imagine until we have an open system to experiment with.
Increased Dynamic Range
Improving overall picture quality
Bring back replaceable focus screens so we can choose our favorite for manal focus.
Better built in lighting. A multi point flash would eliminate most annoying shadows. Bounce and/or wide dispersion lighting could come in handy as well.
Cameras are too expensive.
Focus on the underserved market: APC. Make wide line of lenses and new bodies with low light sensors.
Either make three distinct models with video: entry level, a mid range, and a pro body, or make video a feature that can be activated by specialized firmware for a price. I and many others don't really care about video I would like just a pure still photo camera with fantastic metering, focusing, and low light capabilities.
Internet connectivity in line with the best smartphones. Need to be able to save to compact flash and upload to cloud automatically. Able to email directly from camera in very few steps like smartphones.
Better software and apps available like android/ iOS. Americanized management and ability to react to consumer wants quickly like android/iOS
building a new cheap full frame dlsr, on wich we could use our prime lenses without the 1.4 zoom factor
I would add built in GPS and get rid of video.
The biggest potential improvement for m4/3 and high-end point-and-shoots is improving focus speed and implementing manual-focus aids such as focus peaking.