Originally Posted by Kiss
You forgot a market segment where they would be alone and have it all by them self.
That's certainly Olympus's plan with the 4/3rds system (for which they are inventing a whole new line of lenses, as you suggest). Right now, with sensor tech in its adolescence (not quite "infancy"), the 2× crop is somewhat impaired. But in the future, they'll get beautiful high-ISO results from a sensor that size with all the resulting advantages in compact design, and if 1.5×/1.6× crop dies out, their niche is even more clear.
Meanwhile, back to Pentax -- seems pretty clear that their strategy is to keep the 1.5× crop for the low and medium end (and perhaps for a high-end compact system) and to keep the 645D in the wings to blow away full frame at full frame's game whenever it becomes a market necessity to do so.