Canon holding back......
I think Canon are going to release atleast two more dslr's this year. The 5D mk iii is a complete all round camera but i think there will be a dslr aimed at video (the 4k?) with a swivel screen.
I also think there will be a cut down full frame that will be aimed at the enthuisiast market, maybe around $2000 mark. This could be all the features of 5D mk 3 minus the AF, slower maybe 4 frames a second burst and no dual card slots.
There could well be an announcement later this year for a mega high mp camera being released next year. No doubt Canon would have given priority for the announcement for this camera because of the excellent D800.
This is ofcourse an opinion, but Canon is a very successful company and will be fully aware of the market. The gap for a mid range FF SLR is currently being fulfilled by a 4 year old 5D mark ii. I cant see this continuing for much longer, a newer camera would cost less to produce because of the manufacturing and technology advances in 4 years, thus being more profitable.
I think i am going to return my 5D3 as the features it has, excellent Af and 6 fps are not much use for my kind of photography. I will wait a bit longer :/