I'm just guessing with no information, but I would think this will be Canon's next Cinema move. A 5D C, based entirely on the 5D3 and using the full sensor area, but without crippled video at twice the price. Not sure if the 5D3 sensor and heat handling allow it, but it would explain the horrid resolution crippling of the stills-oriented 5D3.
The price premium vs. competing options would be defended purely by the sensor size (plus vs. body size), for those whom size matters.
I'm guessing this will be announced at Photokina (once they have debugged the 1D C) and out by the end of the year.