I would like to be in a position to add more than 'EXACTLY!" to the discussion, but at the moment that's all my brain will allow (seems my mind if on hiatus also). I say "exactly" because I think what you have stated (Sam genuinely though Dean was dead) is exactly what the writers had in mind. Looking back Sam did make it pretty clear that that is what he honestly thought. It just US - the long term viewer, that couldn't accept that Sam would think he brother was dead. Death isn't really death in the SPN 'verse -but I think Carver misread the long term viewers acceptance of that. He forgot that we can't accept that the brothers let each other die. They never have, so why would this be any different.

Thanks for the thoughts. I am actually quite confident that Carver knows what he's doing in S9. Doesn't mean it will be good or solid (as I am sure the writing will let it down), but I am hoping the intention, and therefore the heart, will be there.