Imagine a traditional FF DSLR design like a Konica Minolta 7D with knobs and pentaprism and phase detect array below with two more hotshoes built into the vertical grip for strobists.
1. make the mirror electrochromic with two sandwiched layers of OLED or smartglass lcd panels The two panels darkened will be reflective and reflect light into the pentaprism and enable OVF while the top sandwiched layer can be used to effect metering and other info into the eye. So we see a optical image with data overlay or a crop factor view if attaching cropped lenses.
2. The two layers of OLED will effectively have total darkness as OLED is the darkest available panel now. The two mirror panels will turn transparent for the sensor to take the picture. OLED thickness is less than 30 micrometers per OLED so incorporating into a standard mirror system is not too hard. Also the mirror can be raised if needed to reduce ghosting effects.
3. The two OLED panels can effectively act as first and second shutter curtain so can act as a very fast global shutter system together from 1/500 to 1/8000 sec producing a very fast x-sync speed ( cutting one advantage of medium formats with their leaf or global shutters and high x-sync speed. )This way the Sony flashes will not have to do any high speed sync multi-flashing which reduces their effective power. Pro shooters with a lot of strobelights will want this for outdoor shoots as you can use the full power of the strobe.
4. The OLED panel mirror can also be used as a neutral density filter to reduce the scenery brightness by programmable stops. It effectively means we can reduce the ISO to 50 or even 10 so as to get building shots without people in public areas due to long exposure time. Graduated neutral density filter for scenery shots or even a crude adjustable neutral density which might be helpful for uneven or irregular horizons/skies, this can be enable using a touchscreen lcd panel on the back for drawing which part of the scenery needs darkening. Might even be good for wedding photographers who have to deal with extreme whites and blacks?
5. Pros have a need to always control their multiple flashes via the fastest method. Copy the Nikon Creative Lighting System. To change flash settings, press the flash popup button to enable either the flash syncs or the flash EV using the dual front and back dials. To change more flash things, do a double press to enable the selection of multiple flash ratios or switching off of main flash EV and only use as wireless controller. Make another two more hotshoes which have seperate on/off switches under the vertical grip for more wireless lighting options.
6. Use a laser grid camera focus assist lamp to produce a square pattern either on the left top of the camera or directly in line. The vertical grip can incorporate one also so that it at the bottom right of the camera. Sony F707 / F828 cams had hologram laser AF systems in 2003. On the subject of AF, why not incorporate a laser rangefinder function in the vertical grip also.
7. Most pro lighting shooters are Visual and kinesthetic minded so need tactile muscle memory dependent interfaces to use their cameras. Knobs best, if not programmable buttons and lots of them. progammable as single or multi press. And also two button press if possible like the Nikon system.
8. Enable custom hand grips for different holds and shooters.
9. When shooting multiple long exposure shots, just use the first dark frame instead of always redoing the dark frame noise reduction as it effectively doubles the waiting time. Only if the exposure time is changed then start another dark frame.
10. To improve the black white dynamic range don't let the camera use the color information ( demosaic ) to reprocess the shot. Get the info right from the four same color Bayer point and use their pixel dynamic range which effectively reduces moire patterns ( due to demosaic ).
11. Speculation, for CMOS sensors, sample the sensor data a few times during the shutter capture cycle to see which pixels are getting blown or overexposure and then use the previous samplings averaged to reduce the brightness for those pixels. This makes for a more filmlike response to the sensor. Can be done if the camera has very good buffers.
12. make the camera able to communicate ( wifi ) with android or iphones to display the live view so you can take very interesting angles or overhead shots at concerts.