1D size? Bleh.
Put it in a 5D body and I'll cry rivers of joy.
By the time this gets released (late 2014??? perhaps earlier though since rumors claim they are going back to the old keep it secret until it is near ready to ship thing (when they did that people complained GIVE US A CLUE WHAT IS COMING! and then when they finally started doing that people complained IT'S RIDICULOUS THAT YOU TELL US WHAT IS COMING A YEAR AHEAD, EVERYTHING IS LATE!) it may be only sixth months to the 5D4.
That could actually be bad since they'd have to dumify the 5D4 to make this new higher tier but not yet 1 series tier look good. Where does it fit by then?
Unless maybe it is: 3D 50MP 6fps, big, ultra sensor, 1DX price (if they fit it into a 5D-sized body and had price lower than 1DX that would be awesome though). 1DX2 is 27MP 14fps, big, ultra sensor, 1X price. 5D4 is 32/39MP 7-8/6fps with perfect 4k video (4x MP as on the C100), small, ultra sensor (the higher MP option there starts making the 3D look questionable though). ultra sensor = finally a new fab and design that gives great low ISO DR. Still seems very weird they'd use 3D as a name though, so I doubt that. 1. 3D not delivering 3D doesn't work well in this day and age. 2. It seems less like an EOS 3 than what the 5 series has become.
That mysterious Canon pyramid slide with a missing spot almost implied that some sort of high-end mirrorless DSLR may be the next big thing though (at least after a 7D2 perhaps).