Leica had CMOSIS to develop a special CMOS sensor for the Leica M. Modern cameras are built around sensor limitations, while the M was built for film. Later lens designs needed to allow space for the exposure meter probe of the M5 and have a smaller ray angle for that reason.
Leica also has a coding for it's lenses and a corresponding software correction.
It is very much possible that some vendor could build a camera optimized for Leica M-lenses, but it is a small market. Development costs per unit would be high.
A full frame Leica-M clone with all the modern electronics and features is very attractive. Leica seems always lagging behind on the feature in the modern world.
However, even with APS-C format, every mirror-less digital camera suffers more or less the vignetting and color shifting at corners, albeit due to the micro-lens. It's usually much more so with Zeiss ZM.
Heard Sony is offering FF Nex. I've seem all the crappy Nex lenses on Nex 6 and Nex 7. Can't figure why it wants to do FF. Better off come out with adequate APS-C lens first.
The flange distance of all mirror-less cameras are much shorter than Leica M. M43 is about 19mm while APS-C mirror-less are around 18mm. Leica M is 27mm.
If Leia M 27mm is too close for the uniformilty on non-Leica-M sensor (the tilted micro-lens?), what's the chance for the shorted flange distance to perform?
Is it conclusive a mission impossible for the mirror-less or Leica M clone without the Leica-M like sensor?
Yes, I understand the FF DSLR with longer flange distance is another story.