My wife is Japanese.
Her brother is a huge Nikon fan (living in Japan) and he reads ALL the extremely esoteric Japanese camera blogs and websites.
Some of the blogs are written by Japanese employees of Nikon and require a password to read them for trusted otaku members only. None of them are in English.
He claims that the Nikon Digital SP-DM has already been prototyped several times and and has been tested with crop and full frame sensors.
One lens already developed is a modern 35mm f1.8 in an M-mount.
The SP-DM has a fascinating advanced fighter-plane style "heads up" hybrid electronic viewfinder/ optical rangefinder with a glowing red rectangle "in focus" indicator, that lights up when the subject within the center rectangle is in range/focus.
There is no traditional optical viewfinder as such, but the finder magnification/parallax is controlled by the traditional Leica M mount mechanical coupling. It does not make use of the Leica lens coding.
It's supposedly an elective unpaid project by Nikon employees done in spare time who will get bonuses based on sales of finished project. If built, it will be made in modules in Japan and assembled in Thailand.
Again, I know nothing about this "for real" and rely on what he has to say, but he is a fanatic and spends hours on end reading this stuff. He's not someone who would be prone to a hoax, he's a senior engineer for a major Japanese firm.