Originally posted by MSM Pentax has a real problem though. As you allude to in your post, there is all that old 35 mm Pentax glass. The legacy glass is at the same time the life line and the anchor sinking the ship. New body sales need to drive lens sales not the second hand market for used lenses. I love the old glass too, don't get me wrong. But, if one buys an older fast fifty then they may likely pass on the current FA 50 mm, for example. I think this is what the other poster was trying to say regarding dropping the K-mount. Thus one has to buy the new stuff. (Then they would really be like Canon.) But, if they get rid of the K-mount, Pentax might as well close up shop.
Pentax' problem is multifaceted, and IMO the existence of legacy glass isn't it. If legacy glass were the issue then Canon and Nikon would be in the same "predicament"; they aren't.
The reason lens sales suck is (let's be honest now) the current lineup isn't complete. Sure, you can cover everything from 10mm to 300mm but not coherently, certainly not with primes and the only path for the cash cows - consumers - is a mishmash of utility zooms.
In 1984 you had the option of buying five different PENTAX 50mm primes. You had the A15/3.5, A24/2.8, two 28mm, three 35mm, the A85/1.8, A100/2.8, M120/2.8, four different 135mm, M150/3.5, another four 200mm, three 300mm, two 400mm, the 500/4.5, 600/5.6, 1000/8 and the 1000mm and 2000mm mirrors. That's just the primes and don't forget the three macros, a fisheye and a 28mm shift specialty lens! I count eleven zooms rounding things off. That was the "current roadmap" in October 1984, and that (combined with visible marketing) is how you sell 24million lenses and become a household name.
The only reason the A* and FA* 85/1.4 are so desirable and pull the money they do on the used market is because there is no modern equivalent. Pentax seems to have the mindset that there's no point in building a full lineup because everybody is buying legacy glass anyway. Well duh, if there's no new glass to buy and you use a Pentax camera then legacy (or 3rd party) is your only choice.
2009: 28 lenses (13 zooms)
1984: 50 lenses (11 zooms)