Re: The Curator.... Who is he? (SPOILERS for "The Day of the Doctor")
^ I'm wondering if the scar is somehow a fake or a substitution (e.g., of the TARDIS's own timeline). if not, then the only real alternative seems to involve the death and dissolution of the Doctor's original body; though whether it'll stay that way is another question.
"Fantasy is an exercise bicycle for the mind. It might not take you anywhere, but it tones up the muscles that can." - Terry Pratchett.