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.
5DIII, 1DX, 8-15/4L, 16-35 f4L IS, 24-70/2.8L II, 70-200/2.8L IS II, 70-300/4-5.6L IS, 200-400/4L IS 1.4x, Zeiss 15/2.8, 17/4L TS-E, Zeiss 21/2.8, 24/3.5L TS-E II, Sigma 35/1.4 Art, Zeiss Otus 55/1.4, 85/1.2L II, 100/2.8L IS Macro, Zeiss 135/2, 600/4L IS II