A couple thingsRe: Sanderson himself seems to be losing confidence. - Edit 1
Before modification by RandAllThor at 01/01/2010 12:40:52 AM
However, he has also been saying that ToM is much more complex because it is less concentrated and cohesive than TGS, and it may take longer.
The real question, I think, is longer than what? I took his comment(s) to mean he needs longer than his January 2010 self-imposed deadline, which, as you say, should still put him in good shape to have a book to us by next Christmas assuming he finishes by, say, May.
It's also possible that since he has to write AMoL itself virtually from scratch (he had a big head start with ToM from the material he'd written alongside TGS), Tor may choose to space out ToM so it's more or less halfway between the two other books.
I'm not sure he would need to write AMoL from scratch. We know that Jordan already wrote the "last scene," whatever that entails as well as the parts of the story he was most excited about; I wouldn't be surprised if portions of the Last Battle fit that criterian. I also think it would be tough to space the releases of ToM and AMoL with any precision given that Tor can't know how long Sanderson will take to finish the latter.