User blog comment:Morganaforever/Thoughts on Merlin's finale/@comment-5253758-20121226143203/@comment-5674726-20121226154202

And how in earth could Arthur come back to life after so many centuries?

Good question. Since Morgana didn't heal him and bring him to Avalon to rest until he was needed again, Arthur was left as a corpse floating on a boat in the lake. We only have Kilgharrah's word for it that Arthur will return, and his track record is spotty, at best. Merlin could be spending his immortal life hanging around a lake waiting for something that will never happen.