Northlight has been told that the high resolution camera coming from Canon will be based on the 4.2 micron pixel design of the Canon EOS 7D Mark II, not the long-in-the-tooth 4.3 micron design of the 18mp APS-C sensors. When translated to full frame, that totals about 52mp. It's also suggested that delays in this camera have come from getting an economical yield from the sensor manufacturing process at full frame.
If true, this will also help the marketing department out a bit, as we expect to see Sony/Nikon to each release 46mp (only!) cameras in 2015. :)
We're calling the camera the “EOS 3D” for now, even though we have been told by a couple of new sources, that this camera will be the EOS 5D Mark IV.