I think it will be around for a while, but don't know how long. Of course, the fly in the ointment is that they haven't been in general stock for a long time, so it's hard to tell what's going on with the camera.
I'm personally getting toward the decision to not upgrade to the D4 as originally planned, but continue to use one of my D700's instead in lieu of it, but upgrade the other D700 to the D800. It lacks the speed, and it looks like it lacks some of the dynamic range at ISO values above 1200, but it has other significant advantages, especially when we're talking about cropping in for a small bird, or for macro, landscape, and portrait work. The general characteristics of noise seem to be on a par with the D700 at equivalent print sizes and darn good at least through ISO 800 at any size.