Very interesting. But there's more to the game than megapixels. Part of the problem is getting that data OFF the sensor quickly enough. And without burning anything up.
A part of what Nikon has brought to the table in the D4/D800 is something we video folk have been DYING for from Canon. Give us the HDMI video out cleanly. Canon has not yet provided a camera that can do it. Nikon has apparently succeeded where others have failed. Additionally, Nikon seems to have successfully allowed decent in-camera audio. That is huge. And 5D had the same sensor issue as the D200. The noise is just unbearable beyond ISO 1000. In most video applications, you don't get to do much cleanup.
If Nikon wanted to rule the roost in DSLR video right now, they'd take the D3s sensor, put it in a D700 body, give it the output of the D800, and, position it for $1500. Canon would not sell another 5D or 7D for video for years. Well not many.