I'm with you on this one Mike.
I should start my own rumor site. I'm chock full of off-the-wall, crazy ideas.
There is not enough profit margin in it. No one their right mind would do it for purely a profit motive. Leica will be the only drf manufacturer IMHO. The only way someone would do a drf is more for showing that Leica is not the only one. I not sure anyone has that big a war chest to playing that type of games w/o the investors going after their heads.
The closest u will ever see is the Fuji ovf/evf hybrid type design.. Leica owns the roost on drf. No one wants to take a chance.. All one needs to c is the Epson drf.. While successful up to a point..it was not successful enough to keep on competing w/ Leica. Any that is MHO.
The Ricoh gxr w/ m module was the only other manufacturer I am aware of that even did anything special to make rf lenses work correctly w/ their sensor. Ricoh has discontinued the whole gxr line. I doubt they would have done it if it was making enough profit for them. I rather doubt they are going to re-introduce a rf like camera friendly sensor like the one they had on the a12 m-module as well. It will be more like if it happens to work, great... Ala Sony a7 or a7s or Nex 5n ..etc.
While I have a Sony a7 to use w/ my legacy lenses, at the end of the day in digital, I am more interested in native lenses for the camera.
Electronic solutions to focusing aids, such a peaking or digital split image (like slr style that Fuji introduced) or the ovf w/ center evf overlay (Fuji x100t) maybe the closest one will have from other manufacturers outside of Leica to help w/ your rf lenses, but I doubt anyone but Leica is going to do anything special to help out w/ the possible range of rf issues as it relates to their sensors.
If I get the urge to shoot w/ an rf camera, I will shoot film.
Anyway as I said just MHO of the reality that exist today. I would be happy to be wrong.. But in reality for me..even if someone else made a drf unless it was under my magic number, I would not buy it...digital is like computers and audio gear... It is a merry go round, always something better within 2 years of whenever u bought what u bought. On the otherhand, if u are happy w/ what u already have, what does it matter what the next great thing is. The only issue is what u got eventually wears out, breaks down, or u have an accident. As it gets older, electronic components that were used in your camera are not available anymore. The best a repair shop can do is hope to have a camera body to scavenge, otherwise sol..digital rot. I am not aware of any camwra maker that controls the manufacture of all the electronic components in their camara bodies, Leica included. I have film cameras that date back to around 1920s or so that work fine today, can't say the same for some of my digital cameras I have had over the years.
Gary
