Originally posted by Clavius
It is actually possible to take pictures with cameras that have no K-mount
It would be a great idea, if Pentax switches to a new "raw" mount, which adapts to either K mounts or other mounts (Canon and/or Nikon) with broader lens supply, including from Sigma, Tamron, Tokina etc), with the help of an adapter system.
Any adapters for such 3rd party mounts may not be cheap, because they would bear licensing costs (and development effort for their lens protocols) but I'm sure many would be willing and happy to pay such a premium.
Advantage to users: obvious and self-explanatory.
Advantage to Pentax:
- less users, including those economically valuable DSLR market enterers, which would not consider the Pentax bodys just because of the limitations of lens choice, or because of the actual price/quality ratios are not satisfying to them.
- Less 'old' pentax users would leave the Pentax system for the same reasons.
Disadvantage to Pentax:
- Pentax (actually Ricoh of course) is making a huge profit margins on (most of) their lenses. Ricoh woudn't want to threat this source of (profitable) income.
For example the Limiteds: only a very few lens elements, lens designs wich are decades old thus license free, have simple sperical-only shapes, and only small diameters. I'm sure they must be dirt-cheap in production, but are sold for 3-digit-amounts, instead of 2-digit-amounts 
No one will blame a company for striving for profitability like that (most printer makers do that since ever: cheap printers but overpriced ink), but that has to be balanced against the threat of DSLR joiners not joining Pentax-K, or Pentax 'oldies' leaving Pentax.
If I was managing the camera division of Ricoh, I would weigh the latter risks higher, esp. for the long run, and would advise my engineers to develop a modular, adapter based mount system.
Unfortunately, good managers are rare. Many are only as smart as the ones in Dilbert cartoons, and very few are like e.g. Steve Jobs. That's the reason why many businesses go out of business eventually.