Dean! Don't put that question on Sam's shoulders. This was one decision they had to be completely on the same page with. If they didn't agree on the outcome it could seriously mess them up completely. Even more than they already were.
"Dude, you've been taking care of me my entire life. I think you've earned a break." He paused, unsure whether to say the words that were currently in his head. Oh well, it wasn't any worse than what they'd done already. "Besides, you took great care of 'little' Sammy." Oh yes, he went there.
As for what happened from here on out? He had no idea.