Hum... it really depends whether their current equipment enables them to manufacture such large sensors. If they don't, then the cost of machines alone would eat up a significant part of the margin.
I would love this to happen though.
I don't expect a possible "close to 645 film sized sensor" Pentax camera to cost 10K USD so "margin" is an unknown variable here (but even if the sensor is to cost . If such a camera will come I expect it to cost at least 1.5M Yen (almost 20K USD) but if Pentax could do at least:
- reliable tethering (this is work in progress)
- modern live view
- maybe some form of movie mode
- make available worldwide all the FA 645 lens range (also on the way to be realized at least in Europe many lenses are in stock and more exotic ones are available to order)
- make available worldwide the new D FA 25 and the new D FA fast portrait lens (maybe with leaf shutter)
- organize a more convincing support network in Europe and North America
I think they would have great chances to sell such a camera with a proportional success compared with 645D did but in the higher end class.
P.S. I know that you will watch closely the next CP+ in less than 5 months, there could be lots of answers on what Ricoh thinks about Pentax MF range.