Image Credit: Nikon Rumors
One of our sources we trust has confirmed for us that the Nikon D5 has 4K video. Thus we are going to come out and stake our reputation on this point.
There may be caveats we are not aware of, such as 4K may only be available in crop mode, or for short time limits.
Time will tell all the details soon enough. We were getting worried that Nikon was going to not include 4K in this camera.