The Ultra-fast 50's are a kind of flagship lenses for manufacturers. The Canon 0.95, the Nikon 1.1, Zunow's 1.1 and the Hexanon 50/60mm f1.2's. It was a matter of pride to make them. From practical standpoint they are in most cases "overkill". I have been seduced by Nocti's multiple times (6 of them over the last 3-4 decades), even the Canon 0,95 briefly and the 60f1.2 Hexanon for a couple of years (the best of the bunch in my estimation). In the end they were all disposed of as I was tired of hauling them around and for my type of shooting, they did not work.
The Noctilux F1 was a Dr Mandler design (Leica Midland Canada), mainly because he did not like the f1.2 Aspherical. Too difficult to make, too expensive to sell and really, not that good!
Leica's sales of Noctiluxes were small (one figure I heard was 200-250/year at its peak) and if you can trace the ownership of a Noctilux, you will probably find that most of them are bought used and go through multiple owners over the decades. Out of my 6, three were bought new (the 50f1.2, one early F1 and one late version with the collapsible hood). The other ones were trades for stuff I felt I needed even less than a F1!!
A superfast 50. a 0,85 or 0,95 is probably quite useless in practical terms. At close focus you have a depth of field in millimeters and even focussing on the eye. you will have eyelashes "fuzzy" and the nose looking like a blob! Focussing accuracy and rangefinder alignment would be critical and almost require dedicated bodies for the lens.
What would be interesting is what the performance would be like with 21st century technology. The Noctilux is an old design (40+ years) and today we have far better technology available for glass and coatings. A new design. using the latest technology could be interesting, though it might have a far more clinical look than the Noctilux of the past. Of course, this is hypothetical as the price for a Leica one would be staggeringly high and my hope is that either Voigtlander or Zeiss takes up the challenge and makes one at an affordable price - they have the technology to equal or even better a Leica effort. If that happens, I might even be seduced by it and get one - at least until I get tired of dragging it around or chasing focus points in the enlarger!