What I'm thinking is that Dean and Cas leave Chitaqua to make it on their own, for the greater good. Cas offers to leave by himself, but without his angel powers he's kind of useless. He's still learning the ropes of being human. Sending him off by himself would be a death sentence, and while Cas probably wouldn't mind because he's as stupidly self-sacrificing as everyone else in Dean's life, Dean's not gonna let that happen. So they leave Chitaqua in Sam's capable hands, who's sad about it, but he understands I guess. Dean jokes about sending him postcards. So off Dean and Cas go into the great blue croat-filled vampire-infested yonder, on a grand adventure of fraught emotions and monster-killing and barely concealed regrets.

In a way it kind of turns the end of 5x04 on its head, because 5x04 taught Dean that he and Sam should stick together no matter what, and yet here he and Sammy are splitting apart again because it's supposedly better this way... Hmm. So is the devil gonna come after Sam hardcore now that he's alone? Maybe they really can't escape destiny. In conclusion, Winchesters can't have nice things.

Hee! <3 I love Saint Becky the Apostle to effing pieces.