Originally posted by reh321 Compare the Super Program on the left side of my signature to "modern" cameras; there are people today who demand large grips, but we did just fine with them back when one hand spent part of its time focusing. I suppose that IBIS might force the body to be slightly bigger, and so might WR, and then there is the battery, but I believe that the form of an ME or Super Program (my first two SLR cameras) are reasonable, and attainable, goals for the size of a camera.
I shot an ME Super from the early 80s until I finally switched to a DSLR.
The problem is all the stuff that
has to go behind the film plane. The battery, motors, and flash capacitor (which is the size of a AA battery) can more or less take up the space that was the film and mirror/shutter mechanism in a film camera, but the sensor stack, SR chassis, main circuit board, and LCD
have to go behind what was the back of the camera. That's at least 15mm of stuff behind the film plane, compared to about 3mm in an ME. So no matter what, the overall dimension mount-to-LCD is going to be about half an inch thicker than a film SLR.
To keep the body thin, you could make the 'snout' much longer (Pentax DLSRs generally do have longer snouts than their SLRs), but there are probably limits to how far the mount linkages can be from the motors, and the motors appear to be too large to fit in the snout and have to be buried in the body. (Unless you want a body as thin as an ME, but with a snout like a 6x7.)
MILCs with a much smaller register distance (~17mm versus ~45mm) can move everything forward into the empty space that was the mirror box and have lots of room left in the body. Some of the Olympus bodies are the size of a film SLR but actually have more space behind the film plane than a DSLR.