AFAIK The D700 "cannibalized" sales if the D3
Facts don't support this. D700 came almost a year after D3 when everybody that wanted to buy a D3 already had done so. There was nothing left to cannibalize and both the D3X and D3S were already in the pipeline getting ready to be released soon. Nikon probably had a few extra D3 sensors lying around and wanted to get rid of those. Furthermore D700 was thwarted by Canon 5D Mk II and didn't sell all that well after all. It had a loyal and vocal following, but small in numbers.
As much as people wanted to believe the D700 was a mini D3 it never was. The autofocus was never at the same level (I had both cameras simultaneously), the FPS either nor the battery life. And with the grip and EN-EL4a battery D700 was actually bigger, heavier, slower than a D3, with almost at the same price and still with worse viewfinder, only one CF slot and worse ergonomics (missing buttons and features).
I had my D700 converted to UV/IR back in 2009 when I bought a D3X instead and upgraded to D3S. I still have it and it serves admirably my ultraviolet and infrared photography needs.
The D800 series is what D700 should have been already back then. Today the trio of D5, D8xx and D500 make a great range of cameras, each filling a different niche. I don't expect D500 to sell in big numbers, but those who want fast FPS with DX sensor will be happy, I'm sure of it.