Originally posted by disconnekt Doubt it, since it'll take sales away from the 645Z.
I'm not certain Pentax would think that way. Remember -- the 645Z is more than just a 50mp sensor. It also has a range of high-quality lenses that give that sensor more room to do its job, a different (in my opinion, better) aspect ratio, and greater depth-of-field when you want it. And I'm not looking to start a flame war (this time), but to a certain extent because people expect to pay more for MF lenses, they WILL pay more for MF lenses, so Pentax can afford to make them "better" than their FF field-of-view equivalents, even discounting spreading that resolution out over greater surface area.
Pentax needs their new full frame to make a splash, and they need to keep up with the Joneses. I suspect the sensor that winds up in the FF camera will have a lot more to do with what Pentax knew they could purchase at the time they started development.