Canon will reduce the price of 5D3 from 3500 to 2500-2800 to fight against Nikon's D600, which will be priced at $2000 (Don't believe D600 will be priced at $1500!!!!)
Canon will release 3D to fight against D800; and 3D will be priced around $3500-$4000
I my opinion Canon release a entry FF camera to replace the 5D Mark II and the price for the 5D Mark III drop next year under 3.000,00 Euro.
It´s possible that Canon release a camera between the 5D Mark III and 1D X in the next two years. But I don´t believe, that the camera has more than 30 or 32 megapixels.