I am sure we can expect a very potent sensor in this camera. I believe Canon has been working on this for a long time, but been waiting to release it. I would be very surprised if they came out with just a tiny step on the evolution ladder from a 1DsIII or the 1DX.
I am really looking forward to a really high resolution, high DR body, to complement the 1DX, which I am sure will be my preferred action and low light body also after this new one comes along.
1DXII, 5DIV, 5DSR, 8-15/4L, 11-24/4L, 16-35/2.8L III, 24-70/28L II, 70-200/2.8L IS II, 100-400/4.5-5.6L IS II, 200-400/4L IS 1.4x, 24/4L TS-E, 35/1.4L II, 100/2.8L IS Macro, 300/2.8L IS II, 600/4L IS II, Profoto B1