I think the DSLR market is evolving fast, and Nikon and Canon are just trying to keep up with each other. In the end consumers with get a better product for less. Although the down side is our current cameras loose their value faster.
The D700 really isn't a factor for me, because I shoot youth sports, and football season will end before the camera will be available to the public. It has the same CAM3500 AF, so no change there, and it will cost almost twice as much as the D300.
Granted it will probably do better in low light, but how much better than a D300 remains to be seen. Even if it has the same sensor as the D3, that doesn't mean that it will perform the same. Nikon may tweak it just so it's a tad better than the Canon equivalent, but not at the same performance level as the D3.
The DX format is a big factor with me, it puts my 120-300 Sigma is the perfect focal length for youth sports. The FX would require longer lenses, and that’s not a possibility on my budget. So there are always trade offs that each photographer will need to review based on their needs and budget.