Ok, here's something that people often seem to overlook. Despite being somewhat outdated, the 5D mk II still sells well. Canon has simply been operating on the principle of "if it aint broke, don't fix it." When people stop buying the mk II, Canon will replace it, most likely with an affordable entry-level body.
Now here's my vision of an entry level FF camera (6D, shall we say?) Put an 18 megapixel FF sensor and pentaprism in a 7D body with slightly updated (read: more consistently accurate) 19-point autofocus and a single Digic V. Maybe give it 5 fps to avoid canibalization of both 5D mkIII and 7D sales. Given that the 5D II with a 21.1mp sensor sells for about $2200, I see no reason why this new body with less MP couldn't sell for the same or slightly less, again still allowing the faster, $500 cheaper 7D (or 7D mk II) to retain it's "poor man's 1D" niche in the EOS ecosystem.