If the "1" sensor is as revolutionary as Nikon says it is and does what they say it will do, it means that Nikon would be able to make a DSLR without the "R", no mirror whatsoever but still phase detect AF. A "1" sensor enlarged to FX format would be slightly above 50 MP if my mathematics are correct. No mirror box and no prism would mean a camera that could be made lighter and more compact than current DSLRs, even when keeping the current the current lens/sensor distance.
Obviously, there would long term be a new family of cameras, more compact and maybe similar to NEX or m4/3, but I would be surprised if Nikon doesn't think along those lines, since they have developed the technology that enables it. And if they do, the 2.7x crop factor of the "1" makes a lot of sense, since a larger sensor camera would be too close to whatever comes in the future.
So the truth is maybe that the "1" is what it is, not so much to protect Nikon's current crop of DSLRs, but to fit better into a landscape where those cameras are supplemented or replaced by mirrorless cameras designed for the enthusiast and professional markets.
Just a thought...