Then Sam and Dean drive away in separate cars.
This is more of a final episode ever idea, based on a set of theories yourshipmentisin sent me.
Demon!Dean is permanent.
Sam starts the Men of Letters over, and invites others to join. He acts as a sort of Bobby figure to them and hunters who come to them for guidance. He also marries, and lives a happy life like he always wanted.
Dean still prefers the open road, so continues to hunt every evil son of a bitch out there. Because when you’re restless and immortal but still Dean Winchester…why not save some people and hunt some things.
Castiel finds a solution to his grace and is a full angel again, but instead of returning to heaven, he prefers to stay by Dean’s side.
That’s about as happy of an ending you can get if Dean is not able to be cured. There was a second half of what happens after the credits, that I may add on later.
While others in the mind palace, even Moriarty, communicate with Sherlock, Mary stays completely silent, barely moving but still intimidating. The room of the mind palace in both cases is a hall similar to where we saw John running in A Study in Pink trying to find Sherlock and save his life. Mary does the opposite in first: she stops Sherlock from finding something to fight the shock, moreover, he imagines her shooting him again in his mind palace, wearing her wedding dress and her ring. For the later “encounter” Sherlock places her in an open space so he can walk round her and see all of her but deduces nothing but the word Liar. Her most sacred truth in his eyes has become a betrayal (already reflected in how she is dressed as a bride as she shoots him) and now Sherlock can’t see whether even the slightest details he deduced about her before are actually true.