We're going through a tough transitional period here where the qualities and advantages of digital are apparent, so everybody wants to go there, but the cost of the sensors is still very high, and so the choices of body styles are limited to those that sell the most. So we have only two remaining big players in pro "35" (Nikon and Canon), only two or three in medium format (Hasselblad and Mamiya, maybe Pentax?) and scattered representatives of LF. At some point, fairly soon I think, we'll reach a plateau where the improvements in sensors are seen as marginal, and then prices will start to come down. When that happens, we should start seeing a variety of camera styles come back -- when the cost of the sensor is no longer overwhelming, we'll see custom backs for whatever LF bodies remain, may very well see some rangefinders, etc., IF the companies that build that stuff are still around, if they've been able to survive the transition.
We'll also see another branch of photography, the chemical branch, which (not to denigrate it at all) will be sort of artsy-craftsy, like platinum printing or the other alternative printing processes used to be. I think that could go on for a long time -- forever -- unless the EPA or some other organization gets on top of the chemistry...
A few years ago, I spent some time messing around with Polaroid slide film, with their little developing kit, and I liked it -- had a completely different feel than standard slide film, or anything I've ever seen in digital. With the ocean of great film cameras out there, good scanners and interchangeable lenses between digital and film, something like that could come back...maybe.
(proud owner of two F5s and an F4, none of which have been used for three years...)