A new 5D next year? Don’t think so.
5D => 5DII 3 years;
5DII => 5DIII 3.5 years;
5DIII => 5DIV… 3 to 4 years probably.
So it will be well into 2015 and probably 2016 before we get a new 5D.
If the successor for the 5DIII arrives later than 2015 then I doubt that I'll buy it because by then I expect Oympus and others to have increased the IQ in m4/3 and other smaller cameras to the point where I'm happy. I also expect by then that their AF solutions to be just as good as anything in a DSLR.
Already the Nokia 808 PureView is able to give the D800 a run for its money so...
Sure, people will still buy the 5DIV if it arrives in 2016, but it won't be a very interesting proposition as a new camera.