Pentax has scrapped its announced plans- put on hold a year or so ago- to release a digital 645 body and new lenses. They stopped production on the 645N and 645NII quite some time ago. What medium format camera are they supposedly "making?" Not that the 645's got much traction, the 6x7 was really the only unmatched MF camera they produced- and I've have gotten a Mamiya rangefinder instead if I'd really been thinking clearly when I got mine (you want mirror slap- the P67 was the king of mirror slap!)
So no, Pentax isn't "the only brand which makes mid format cameras"- they're the "brand which used to make medium format cameras prior to their takeover back before the management team got thrown out on its ear" for trying to resist the takeover at the last minute. Hoya seems to have replaced the "we can compete at the high end" team with a "we can compete in the middle" team. If, as it seems the numbers say, they lost share in a growing market last year, then next year will be particularly difficult, because this year isn't looking all rosy.
The new Hoya-owned Pentax is a shadow of what it was, and their announced plan to be third in the DSLR market is frankly looking simply unachievable unless they try to count Samsung's production- and let's face it, Samsung has over 6.3x the market capitalization of Hoya, so Pentax isn't the dominant player in that relationship by any stretch of the imagination (~$103B vs ~$16.3B.) Pentax itself had a market cap of just $695M at last year's takeover. Hoya aren't looking particularly healthy market-wise at the moment either.
First of all, this doesn't explain exclusion of Pentax from brands list. And I believe its market share is more than of Konica-Minolta, Sony or Olimpus.
Secondly, from Pentax official website it isn't clear that medium format cameras are discontinued. While all other film cameras are labeled as "discontinued models", medium format are NOT:
http://www.pentax.jp/english/imaging/filmcamera/medium/index.html
And digital 645 may also appear sooner or later.