The one thing I don't like about this is that we suddenly jump from Smith being the 11th Doctor to the 13th! It certainly seems very artificial. Moffat wanted to deal with this issue during his tenure and forced it to happen.
I don't mind the Doctor getting a new set of regenerations, or if he has to worry about each additional one as the series goes forward. I just don't want another character to assume the Doctor's identity as one rumor suggested. The show needs to be about the character that we've followed since the Unearthly Child.