A few of you have noted in emails that you thought I had been hinting at a change to Nikon's phase detection autofocus system for some time. Indeed I have, though I've tried to be subtle about it. That's because I couldn't figure out how the changes played into what might be the D4. I don't expect a D4 to be mirrorless, after all.
But let's make a really simple jump: what if Nikon took Quiet Mode and Mirror Up and combined them into "mirror out of the way mode"? Camera still takes photos normally with the mirrors and optical viewfinder, but if you're willing to go to Live View/Video, it also takes photos quietly with an electronic shutter and no mirror action. There are pluses to both approaches, so it's really the best of both worlds. Indeed, it answers a lot of user requests all in one package, doesn't it? Truly silent capture (not just quiet). True mirror-up capture (no need to bring mirror down). Full time video autofocus that's usable. Optical viewfinder in normal use. The list goes on.
Of course, since this technology is Nikon's and requires a Nikon sensor, that implies that Nikon might also move to all Nikon sensors at the high-end, too (they're already close, with only the D300s and D3x being Sony sensors).
Note that the D7000 (and now D5100) moved a step closer, too: they no longer return the mirror down in Live View unless flash is involved (to get the flash exposure). So if we put all the pieces together with the Nikon 1 technology, we should get close to, if not completely, to a workable hybrid system that has big benefits to the user. This also makes the leaks that I heard last year make a lot more sense, as now they have a context that better supports them.
That said, this isn't a prediction, per se. It's simply a statement that many of the sub-pieces are all slowly pointing towards a common possible end-point: the mirrored/mirrorless DSLR. It's just a hypothesis on my part at this point that this is where Nikon is headed. Personally, I hope it proves true.