>>IMO, it's because Canon is finally shipping the 6D.
>this presumes the buyer would be choosing between a 6D and a D600
Thus Nikon holiday prices a bundle deal of body and lens. Seems logical.
While Nikon allows people to use their DX lenses on FX cameras, that is not a possibility for someone upgrading in the Canon world. So it is a way to attract people away from DX sensor Canons to FX Nikon.
Just a perspective,
Edit for typo
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