The RX1 is a trial balloon. Sony is willing to take the financial hit to see if there is a market for such a camera. If it even has a lukewarm response Sony will plow ahead with a smaller / ish FF camera that takes interchangeable Zeiss lenses, and probably M mount lenses as well.
What I can't figure out is where Voigtlander has been in this battle. If they developed a FF rangefinder that had the IQ of the Epson, and didn't leave the customers in the lurch with crappy customer service, I would run out and get one.
And yes, Fuji will also get on the FF bandwagon, even at the risk of alienating its current users, if the IQ is as good as the current line up of cameras, and the price isn't prohibitive.