My take on the whole 'entry level full frame' would be if the nikon d600 does turn out to be a $1,500 ff camera, then to compete [If they want to] canon will either:
A] Lower the price of the 5dmkii even more to make up for the ancient af, or more likely..
B] Bring out a new ff body using the 5dmkii sensor and the af from the 7d and a possibly a plastic body.
They've been making the 5dmkii sensor long enough for it to be fairly cost effective I'm guessing. Using that sensor, or a tweeked version, combined with a 7d af will match it more evenly with the d600 than the 5dmkii and still make the 5dmkiii seem like a decent upgrade and keep from cannibalizing sales. The body will probably be plastic to keep costs down.
7d af would be a good choice because it's infinitely better than the current 5dmkii. I know its not close to the supposed 39 af d600 but canon have nearly always lagged behind on af points to nikon [except 5dmkiii] so there's nothing new there. They could even do around 20+ af but I don't think they would want to approach a too high number because this could really damage mkiii sales.
Fps will probably be around 4, again this will be competitive to the d600 but a step down from the mkiii.
This is all complete guesswork however