Originally posted by gazonk I think only Leica can sell MF cameras these days, and of the other things you mention, nothing is really expensive compared to the FF sensor.
I'm not necessarily convinced that only Leica can sell MF cameras. Many medium format photographers have paid tens of thousands of dollars for digital backs. Tens of thousands! Just for a digital back!
I'm not convinced that only Leica can sell
anything. That's loser-talk. If Pentax determines what they will and will not do simply by looking whether there are currently people purchasing a product that is made by a competitor, they will never be leaders in anything. If they have decided that they are not capable of selling products that aren't already popular (which is clearly not something they have decided), they will have resigned themselves to being followers, not leaders.
It is true that Leica has success in some areas that other companies don't because they have a powerful brand...but they have that brand because they have built it. Through offering products (or an image) people wanted. In order to do that type of thing, you have to start somewhere. Pentax has obviously chosen to start with the Q and the 645D.
In the last 5 years, there has been an onslaught of camera types that simply didn't exist previously:
Micro 4/3
High-end compacts with fixed lenses (which represent the poorest value proposition in all of photography, yet have sold like hot-cakes)
Consumer-priced high-definition action cameras (again, with fixed lenses)
Lytro
High-end mirrorless fake rangefinders (Fuji X-Pro 1)
Fuji is an interesting case, in general. The x100 is literally a terrible value proposition. It is extremely expense, and is one of the least versatile cameras out there. However, the few things it does offer (compact size, an interesting viewfinder, and exceptional image quality) are things people value enough to pay a lot of money for them.
I'm positive a minimally-featured full-frame camera with an interchangeable lenses could be made and sold for well under the cost of an X100. and, while no individual component of an SLR may cost as much as the sensor, surely the other components (autofocus system, high-speed shutter, SR system, high-speed buffer and processor) must add up to several hundred dollars.
A digital LX is a wonderful idea, too. But it seems like it would be more expensive that something with less high-end features.