Originally posted by Kunzite "Sony, Olympus, Samsung and Panasonic" - I doubt they would care about a niche market.
Fujifilm? They don't make rangefinders either (though their X100 and X-Pro1 are made to looks like one).
A K-mount RF, that would be impossible; a RF needs a mechanical linkage between the lens and the RF mechanism, which of course the K-mount lacks (doesn't need it).
Fuji though has a really long history of RF cameras in the Medium format market and produced them until very recently. It made complete sense for them to make one. It would make sense for Cosina as well (they did partner on the Epson RD1 which was essentially a digital Bessa) but they have stated no interest in pursuing a digital RF at this time - they have found their niche too Affordable FF rangefinders
through film)
Sony and Panasonic not a chance - the Nex 7 is Sony's RF. Panasonic would just need to do a modest change to one of their bodies for the same idea.
Real Rangefinders require a quite complex VF mechanism for focusing and it is expensive to produce. I'm sure Fuji took their route because in many ways it is the better more modern alternative
Like I said previously not a chance we will see this type of design from Pentax, even under the Ricoh brand it's highly improbable - the M mountor is what they are doing for the RF client
As pointed out by others their are many limitations to an RF system. Personally I love shooting with one but cannot afford to shoot Leica digital (or for the most part Leica) If I had money to spare not headed for Pentax it would be for a Bessa kit with 2 lenses, but i'm not certain about how long they will make Bessa, In Canada their hasn't been a dealer shipment in close to a year according to my dealer. he has sold off all his bessa voigtlander product and picked up the Zeiss (a beautiful camera that)