Originally posted by normhead IN answer to the original question then... in one of the Pentax Executive's interviews one of them said the K-01 has a design flaw that prevents it from being effectively upgraded. A new mirror less would have to be designed from scratch. .
I suspect, have no proof, that the design flaw which he talked about, was the decision to go to the XS K mount. The xs design allows some specially designed K mount lenses to sit partially within the old mirror box area. This helped achieve more "mirrorless" compact overall dimensions. The brilliance of this idea was it allowed existing K mount lenses to be used on the K01, but also allowed some new lenses to designed to reduce the overall lens+body thickness dimension.
I think what torpedoed the K01 was not the xs design, but the outfitting of the body. Some nice features were left off the K01 compared to the competition, e.g. the Nex mirrorless had tilting lcd screens, while the K01 didn't. IR ports were reduced from front and back on most Pentax dslrs to front only. HDR capability was cut back if i remembered right. I felt irritated at the design when it came out because i had planned to buy one, than the actual camera was reviewed and too many features that i liked on my dslrs had been removed or limited.
Even so, i expected to see a K02 which would rectify the problems. When the news came out that there would be no follow-up, i bought 2 Nexes and haven regretted the decision.
So the design flaw, perhaps, in Pentax's mind was not coming out with a new mirrorless mount when they had the opportunity. XS modified K-mount didn't capture the public's attention. Like Sony's e mount did with the Nex. Today, one can actually buy a tilting screen on a Pentax DSLR, but at a price tag of $8500. :-( Hopefully it will be exported to Pentax aps dslrs in the future.