There is no chance we will see a new 5D for at least a year. It just doesn't make any sense to release it anywhere close to the 1X. Not to mention, the traditional difference in release has been 5D a year after 1Ds ii, and 5D mkii a year after 1Ds iii.
Yeah it does if you actually look at who would potentially buy a 5D MkIII v a 1D X ... its all in who they are marketed too and what is on offer within the bodies.
Canon will not look to butcher their line up by making similar bodies ... there will be significant differences that will be enough for anyone even considering a FF to disseminate between the two (and any other FF they may bring to market).
In many ways, the 5DII 'butchered' the 1DsIII sales, and many 1Ds customers got a 5DII instead for the video and other reasons. I agree that Canon will want to avoid that in the future.
The thing is, as the saying goes, you can't have your cake and eat it, too. Canon does have to differentiate the 1D X from the 5DIII, and there are a couple of ways to do that. One is time - the 5DIII comes out a year, or more (!) after the 1D X. The other is features, and especially if the 5DIII is going to have more MP, count on it being substantially crippled in other ways - most likely frame rate and the AF system. From a marketing standpoint, the two ways are probably on a continuum, i.e. the closer in time that the 5DIII comes compared to the 1D X, the more crippled is has to be.
So...people waiting for a 5DIII - do you want it announced on November 3rd, if it has 26 MP, 4 fps and the exact same AF as the 5DII? Do you want it announced in March when the 1D X comes out, if it has 30 MP, 4.2 fps, and the 9 cross-type points of the xxD line? Or do you want to wait for a late 2012 announcement with 2013 availability, if it has 36 MP, 4.5 fps, and 15 cross-type points?