As long as I'm still crying over the end of Merlin the show anyway, I was doing some thinking about the future of Merlin the character.
Personally, I don't think Merlin will ever go back to Camelot. There's nothing for him there now. Gwen doesn't really need him, though I'm sure she'd welcome him with honors. Gwaine is dead, he was never all that close to Percival that we saw, and Leon outright doesn't give a shit about Merlin and never has.
That leaves Gaius. Merlin might go back long enough to say good-bye to Gaius, though more likely Gaius would have to come find him. If he had time, since he's now chief adviser to a newly widowed queen, and Gwen does need him. More likely, I think Gaius will make Merlin's favorite meal every night for the rest of his life, waiting for him to come home.
I can't really see Merlin ever straying very far from that lake. His devotion is to Arthur. He hasn't been released from his destiny just because Arthur is sleeping in Avalon now. He'll wait.
So what are your thoughts on Merlin's future?