With the advent of large sensor interchangeable lens video-specific cameras that are affordable (fs-100, fs-700, etc.) I think the days of DSLR video are more or less coming to an end anyway. It will fall back to being what it was intended for: a convenience facility for photojournalists that primarily shoot stills and don't want to carry two cameras. I shoot both stills and video roughly equally and would like to be able to have my 5d3 as a B-cam and even an A-cam for narrow DOF shots, but Canon has, sadly, crippled the resolution. :'(
The D800 is of no interest to me; my next stills camera move will probably be to medium format. Medium format video would be truly awesome.
Canon is going to try to wring some money out of people (via the overpriced C300) as they ramp up their cinema division, something they can only do because of the runaway success of the 5d2 and the subsequent vestment of all that EF glass. But with the fs-700 easily adaptable to EF or any other glass, and the Zeiss CP primes having interchangeable mounts, those margins will not be sustainable for Canon. I think they have made a big mistake here with the 5d3 resolution: they could have sustained that branding and that franchise, undercutting Sony and Panasonic, but they've had internal interference with their own opportunity. Positioning a 1080p cam against RED's 4K cam for a similar TCO was a blunder they shouldn't be protecting.
The 5d3 does beat the D800 in video, soundly. But who cares? Nikon is a non-player in video, even though it had the first DSLR video, and Canon has far bigger threats on its horizon.
We will check back after NAB.