Originally posted by Kunzite Yes.
In an older interview (the translation is still here, on some topic I think) a Pentax Ricoh official said that the 645 with its larger mirror would make most sense for a mirrorless.
It would be a pity because of that huge, bright optical viewfinder; but from an image quality point of view...
I think you are making a reference to the 2011 interview with Toshiyuki Kitazawa, then Head of Business Development:
Originally posted by Toshiyuki Kitazawa: 北沢 645 ですが、そのうちミラーレスを作りたいですね。 理由は一眼レフのミラーショックです。この微振動ってかなり画質に影響しているんです。 将来的にはフルサイズや645でミラーレス化をねらいたいなと思います。
Kitazawa: Well, regarding the 645, sooner or later we will want to make it into a mirrorless. The reason is the mirror shock inherent to SLRs. Those very tiny vibrations do have an effect on the final image. I think in the future I would like to pursue mirrorless full-frame and 645 cameras.
Source:
Translation of Kitazawa Interview - PentaxForums.com
It was made clear later on that Kitazawa-san only expressed personal views. However, the success of the Fujifilm GFX and Hasselblad X1D cameras has proven that his perception was right.
One year after (in October 2012), Kitazawa-san had to fall in line and toe the party line:
Originally posted by Toshiyuki Kitazawa: First, there is a trend that is moving forward to higher IQ among whole this industry includes manufacturers and consumers. Meantime, mirrorless segment is moving forward to smaller size. Even though there was possibility to bring FF into this segment, it was our conclusion that APS-C should be the utmost size for mirrorless segment.
Source:
DC Watch: Interview with Toshiyuki Kitazawa, Pentax's Head of Business Development - PentaxForums.com
The latest official position on the topic, at least the latest I know of, dates back to Photokina last year:
Originally posted by Ricoh Imaging: RICOH is monitoring the market situation for medium format with regards to mirrorless versus optical viewfinder. Given the advantage in image quality medium format will continue to be supported in one form or another.
RICOH feels that there will be a market for cameras with an optical viewfinder in the K-mount arena for many years to come, because many photographers prefer an optical viewfinder. DSLRs and mirrorless each have their strong points, and RICOH is closely watching the mirrorless market and studying how users want to use their cameras and which features they expect. At this point RICOH has not decided if they will add mirrorless cameras to the product lineup, but they don't exclude anything. The deliberations regarding mirrorless also cover the 645 format and decisions made could vary by format. The focus is on how the photographers want to use their cameras and what they expect from them; this will drive decisions about format (APS-C/FF/645) and type of camera technology for future products.
Source:
Interview with Ricoh Imaging - Photokina 2018 - Photokina 2018 | PentaxForums.com