None of this has much bearing on Pentax. In effect they resigned from the fray three or so years ago to concentrate on their existing customers who are K-mount DSLR users. I doubt they would want to risk splitting or alienating their userbase so maybe any mirrorless venture would come later or solely under the Ricoh banner. Imagine the reaction if it became apparent that, say, new 85mm and 35mm f1.4 FF prime lenses were being delayed in favour of a new mirrorless line.
A vitally important lesson from Nikon and Canon (and Q-series!) is that a mirrorless camera with a new mount
must be accompanied from day 1 with an adapter to use existing lenses.
If Pentax brought out a mirrorless camera plus comprehensive adapter for K-mount lenses, there is no need for the the K-mount userbase to feel alienated. It would send the message:
"The existing K-mount userbase remains important, now and into the future, and these new cameras provide
extra options for people with an investment in K-mount lenses".
For this reason, it would not even be necessary for Ricoh/Pentax to release new lenses, that
only work with the new mount,
on day 1. They could just extend their roadmaps, and develop and release new lenses for the new mount when there are
specific reasons to do so. (There are reasons for buying mirrorless cameras other than new lenses!)
I'm an "existing customer who is a K-mount DSLR user". I've owned (and in some cases still own) 9 different Pentax K-mount
digital SLRs. (And also some Pentax
35mm-film SLRs). I've owned (and in some cases still own) at least 18 different Pentax K-mount lenses. I think 23 such lenses in all, in fact.
(Plus several non-Pentax K-mount lenses).
I wouldn't feel alienated by a Pentax new mount for mirrorless lenses as long as there were a suitable adapter. I would actually be encouraged that Ricoh/Pentax were taking a broader view that might prolong their future. I would examine the specifications for such cameras, and might buy one, (to accompany my existing cameras), if I thought it would offer some useful benefits for me.