Thats the most one sided contract ever. Why would u let them block your video while theyre slowly eating away your market in stills :-/Canon, as stated above, will protect their C-line. Nikon's got nothing above this and could have easily made a 24 MPX FF model, with a 17.6 MPX 4:2:2 10-bit 4K and 220 Mbps H.264 to QXD cards. I mean, they are basically 3/4th of the way there. The reason they didn't go all the way is a corporate non-competition agreement with Sony. In fact, this 3-minute 4K recording limit is the most blatant example of product crippling that I have ever seen. I hope people treat Nikon with the disdain they deserve.
As to the convergence of stills and video, it's already here with the sensors. It may never get here with the workflow. But this only implies that the same 3/4th of electronics will be shared and 1/4th will be slightly different.
* This 3/4th common design obviously excludes the $50,000 101 MPX monsters like Phase One or the ultra high end video cams like F65 and Alexa65.