I am with RRRoger on this. The D800 seems to be the upgrade to the D3X.
As a smaller sized D3, the D700 seems to have been orphaned on the "direct upgrade" path. The D3 has been updated with the D4. If you used the D700 as a mini-D3, the D4 would seem to be the high-cost upgrade path you are probably being pushed to for a high-ISO high-FPS sports camera.
If you were using the D700 as a general camera, or an FX landscape/studio camera, then you now have a choice to make on whether you want the megapixels or the ISO-FPS abilities.
Or you can stay with the D700 because it is still a great camera! I upgraded to the D700 from my D200 back in November because everything in the D700 was an improvement over the D200, I wanted a mini sports shooter, and the D800 was rumored not to be going in the direction I wanted.
---------+---------+---------+---------+ Joseph K Seattle, WA, USA