I think it will be high frame rate because high frame rate is what Canon does better than anyone else. I have also been poring over Canon patents for the last month, and they seem to have quite a number of parallel readout and parallel pixel processing patents for high speed readout of high megapixel count sensors. Canon has also prototyped a 120mp sensor with a 9.5fps readout rate using some combination of block and row/column parallel readout and on-die image processing.
I see no reason why that technology could not be applied to a "measly" 30-40mp FF sensor to achieve at least 6-8fps. I also see no reason why ISO range would have to suffer. High ISO capabilities are not mutually exclusive with low ISO capabilities. On the contrary, high ISO is limited by physics, while low ISO is limited by electronic noise sources. Canons maximum well capacity is already more than high enough to fully exploit 14 bit data, as well as fully exploit 16 bit data...the only thing in the way is their high read noise. That could be solved with a parallel digital readout approach that applies digital noise reduction similar to Sony. If Canon solves the noise problem, they could easily have both quality high and quality low ISO performance.
Doubt it. Actually 5d3's data throughput is lower than d800's or 7d's and on par with d600's. 6D's is on par with the rebels!
Oh Canon surely can do FPS better than anyone..., but its reserved for the top dog only as is a bunch of other features.