Voigtlander will never do this but a guy can dream right?
I have a Hassey SWC and CV made a great viewfinder for the 21mm equivalent lens. Well, my request is that they make a viewfinder that is a stand alone rangefinder. They would have to fix a gear to the focus ring on the lens and have that gear connect to the viewfinder. Then I could use something besides zone focusing on my SWC!! I would be in heaven! Voigtlander is the only company making 21mm viewfinders (in the R4 series) so only they could do this. Hey a guy can dream right?? Or maybe make one myself if wanted to destroy my R4M...
Next on the list (more reasonable). More models in the Bessa Lineup but with fewer framelines. I love my R4M because I love wide angle and my 21mm Zeiss is great on it. But I don't think I will be putting a 35mm lens on it... instead I will just get another body (R2 or R2M) and put a 35mm on it. So if they could make a body with just 35mm framelines and make it cheaper then I would do that. Have one body for each focal length (or the most popular) - 21mm, 35mm, 50mm and 90mm. If that would make it cheaper to produce (probable) then I would prefer to buy that.
Also make some stuff in different colors... chrome, olive, grey, white.
Use leather on some of your bodies! Sell some editions where leather is an option instead of rubber.
Lastly - Something I don't care for you to make is a digital. Keep on with film. When the huge electromagnetic pulse from the sky comes down and renders all those digital cameras useless I will be happily snapping away with my R4M.