The nightmare scenario is Pentax moving only when it forced to do so.
As happened when digital was first introduced.
For one, Pentax had a prototype 135-format DSLR long before Nikon did, only that Philips couldn't deliver on their sensors. They certainly wasn't "forced" to go digital. Would you say that Canon "forced" Nikon and Sony to the 135-format game, too? No, Canon didn't force them to go that route. It was of their own volition that they went that way.
And two, how is that a nightmare? If and when Pentax does move to 135-format, it means that the technology is cheap enough for the rest of us to afford it. I'm probably not as well-off as you are, but $2500 to me is still a lot of money to spend for the wonders of 35mm sensors. Most of the "few remaining customers" (God forbid! I'm not cool!) of Pentax are either those who are fully invested in Pentax glass already (like Jim King) or those who saw great value in what Pentax offers (like me). To force 35mm sensors at this point in time is folly for a brand that is slowly trying to rebuild its rep in the market of this new generation. The K-m is a step in the right direction, really, and they can squeeze APS-C technology still for the next few years while making good enough profits to put back into R&D for other more pressing needs - better AF, better FPS, etc.
Sure, I'd love 35mm sensor technology, but at a reasonable price. Not everyone here is well-off or makes a living out of their photography.
As before, I think a lot of people here are always hoping Pentax to be Nikon and Canon. If you're really not that happy (perpetual gloom and doom, Pentax is passe and is always left behind), it's much easier to switch systems now than ever before, with the internet, eBay, etc.
I understand everyone who clamors for 35mm sensors in a Pentax body, but it's not a death knell for Pentax to reuse the Samsung sensor and not introduce a 35mm DSLR ASAP (Olympus and Panasonic would've died long ago if that was the case). By most accounts (even from esteemed reviewers), it's a perfectly usable sensor still.