>Well, technically, they do. It's just going to cost them more >money.
No, not really. There will soon be nothing in the range that has the smaller form factor of the D700, emphasises high-ISO performance rather than pixel count, AND fits in the price gap between the top DX camera(s) and the single-digit series.
That's not to say that Nikon inevitably has to keep that particular niche filled, but I can understand that a D700 owner looking for "the same but better" might feel he/she has been left out.