Nikon can't continue to sell D700 in Japan due to new Li-ion battery regulations. It looks like the next-gen cameras were slated to replace all cameras using the old battery, so Nikon probably intended the D700 to phase out. But, Nikon hit a snag in making the D800 so revolutionary, they took it completely out of the same user bracket as D700, which got some D700 users up in arms.
Anyway, now it looks like at a stopgap for this issue, Nikon will continue to produce the D700 for sale outside Japan. I can't imagine however that this is considered a good long-term solution for Nikon, as they should eventually want to get all the new cameras onto the same battery platform, and the stopgap does nothing for customers in the mother country.
Nikon's strategy long-term must either be to hope people stop wanting a D700-style camera, or to introduce a new FX camera tier somewhere around the $2000 price point, which puts it very close to D300s (D400) territory. With the D7000 moving up-market from D90 by adding a magnesium shell, weatherproofing, and additional external controls, this raises a question of where the D400 fits between D7000 & D700 replacement, which squeeze this segment from both ends. The D400 could be D7000 sensor in a new semi-pro body, it could be a higher-density (24MP) DX sensor, or it could be a D4 (FX) sensor with less speed, which would make D400 logically replace the D700. Given the D7K has been out for 18 months, I think if the D400 simply adopted this sensor, we'd have D400 already. Of the latter 2 options, I'm thinking more and more a 16MP FX D400 might make the most sense, although this eliminates the high-speed DX camera which would be a loss I'd personally mourn.