The K-3 is a real winner... a K-3-like FF camera should do well even if slightly larger to accommodate the larger sensor. But that puts it head-to-head with popular Nikon & Canon DSLRs.It sure could, but I have a feeling it'll be more like the K-3 II.
Seems to me Pentax would want to find a niche with minimal competition, and expand it. As with the 645Z, where the only direct competitor is about twice the price. But given the 645Z option for a sensor larger than APS-C, I wonder if a FF DSLR is in Pentax's future...