Never.

Nikon has two current models and Leica has two also. I assume neither company is making a lot of money on these cameras.
It was a shame to see Nikon discontinue the FM3a as it is one of the best Nikon analog cameras ever produced.
Nikon did produce a limited number of thier original rangefinder a few years ago but they had to reverse engineer the camera. I can't believe they made any money but the effort was more a labor of love. Leica tried to reverse engineer the M3 and produced the MP and an MP3 like varient of the current MP. The reason was consumer demand and disatisfaction with the M6 comparison with the M3. I think they made and are still making some money on sales of the MP. I do not forsee any new M analog cameras from Leica as the current MP and M7 appear to completely satisfy demand.-Dick