Stop making sense walchan!
While I like Ron's fantasy request for sentimental reasons, I cannot see Ricoh releasing any new long telephoto lenses. 500 mm lenses are used primarily by sports and wildlife photographers who are able to justify the big costs. Not to mention that Pentax doesn't make a high-performance camera like the D300s or the 7D to effectively use the lens.
Besides Ron and maybe five or six others who will swear by this forum, who else is going to buy these expensive lenses? As of this late afternoon, Pentax or K-mount lenses do not appear anywhere in Amazon's top 100 best-selling DSLR lenses. The real question is whether there is a market for new K-mount lenses, let alone $6,000 K-mount lenses.
How many Pentax users are contributors to Sportsshooter.com? Or how about the Nature Photographers Network? Maybe one hundredth of a percent. Like a rounding error. If you want Ricoh to be smart stewards of the Pentax brand, then they will not do this. Anyway the engineering behind a professional fast 500mm lens with an ultra-sonic motor, IS, and precision control is um, a little beyond Pentax capabilities--let alone QA issues--right now.
To me, if you have a need for a high-end long lens and can spend the $6000, you might as well spend another $1500 and get a dedicated Canon or Nikon body that stays attached. It's not like you are abandoning your Pentax for all other uses.
SmertZ