Upload & Sell: Off
I don't agree with those making assumptions about minimum body thickness. With the constant progress of miniaturization, who's to say what the technical requirements would be.
So I've been thinking about it, and I think a Nikon FA/OM-4 configuration is the way to go. Mirror, Pentaprism, meter, basic PASM logic.
The only thing, and now we're getting really crazy, would a new mount with a fairly shallow registration distance. However, the new mount would have the ability to read and operate the aperture pins and levers of various other lens mounts with a proper adapter. Enabling open aperture metering, and PASM modes on appropriate lenses. Like a Tamron Adaptall in reverse.
anyways it's all a dream because we are probably not going to see the combination of a stripped down retro style, pentaprism, FF camera. Fuji is going to stick with retro and crop; Sony will probably do FF but it will also be mirrorless and follow their (nonexistent) design and ergonomics. Canon and Nikon are too committed to selling cameras to soccer moms and uncle bobs to gamble on something this niche.
Come to think of it, Pentax is just quirky enough that something like an ME-Super D (god I hope they use that name ahha) is not entirely stuck in the land of fantasy. But you can never count on them to release anything.