I think that if Nikon were to produce a digital rangefinder with a new lens mount, not an S or M, but a totally new lens mount, it might work. If Nikon were to partner up with Zeiss and offer at least 4 new Zeiss lenses for the "SP-D", and market the new system as a high quality, high resolution, great low light performer, I would buy into the system. Think back to the Contax G series. Many either hated or loved the G1 and G2. Many people bought into the system, and I am sure that there will be many who would buy into the new SP-D with Zeizz lenses.
Why no S mount? S lenses are getting more scarce every day. M mount arlready has the M8, so if Nikon were to take the plunge why not do it head first and build something innovative and revolutionary from the ground up?