Regarding viability of Leica's film bodies I wonder how many total new film bodies are sold in a calendar year. I'm quite sure Leica would never release that information but it would be interesting to know.
As a WAG I'd say less than 1000 of all types (MP, M7, MA) worldwide.
The used market still seems healthy though I cannot see how that helps Leica's bottom line.
The 1000 number may be high, to be honest. Since the cameras are basically hand made anyway, they probably run the production line for a while, then assemble the parts as needed. The parts don't rot so they are probably sitting in boxes.
So to answer the ORIGINAL QUESTION XD
Are Leica still "sought after"? No, not in any sense of a large camera company, but this is nothing new. The fact is that Leica is "worth" around 860 millions. So it's not a tiny company, especially when in 2011, it was worth around 400 millions, and in 2004, less than 100 millions.
The bottom line, as I have said so many times, is simply: if you think you like RF photography, spend $1700+ for an M7, and as little as $500 for 50/2, 35/1.7 and try it. If you don't like it, sell it and you will not lose money. If you like other cameras, then don't worry about it. Go out and take photos.