Wonderful coda to the episode. I hope it doesn't end that way, that Sam (and Kripke) can find another way out, but it is a plausible solution. I'm glad that you acknowledge that the real threat is not so much that Dean will die, instead the real worry is that Dean will go to Hell for all eternity. I totally believe that Sam will do anything to prevent that. I also believe that Sam would not be able to live with himself if he killed Dean, especially if he believes "what's dead should stay dead" as much as Dean did last year.