I'm pretty sure Pentax went with the one that offered the best specs and quality vs. price when they started the developpement of the upcoming body.
My guess is that new Pentax DSLR will have more than 12 Mpix and use a Sony sensor. But maybe the K-x's Sony sensor will make it into yet another Pentax body...
It could also be the new Sony CMOS sensor (15 Mpix, 4 channels) or the new Samsung CMOS sensor (14.2 Mpix, 8 channels)... I doubt it's gonna be the Samsung sensor though, since this one was only announced a few weeks ago. The developpement of the next Pentax DSLR probably started before that.
Rumors of a new, 21 Mpix (from Canon?) full frame Pentax DSLR, along with the possible introduction of a new Micro APS-C EVIL camera, just add up to the confusion.
Quite frankly, I don't know anymore.
Pentax has been quiet for quite a long time, so they must be up to something "big" (like a new lens line-up, FF or Micro APS-C), so anything is possible here.