It totally harked back to the typical season one structure of the episodes, with the supporting characters mirroring the Winchesters. I loved when they did that, just the elegance of the structure and also how it allowed for so many interesting guest characters.

I actually don't know, I think it can be read both ways, and that is maybe part of the point. Is Dean now a ghost of his old self? would be another possible reading to add to the ones you mentioned. They all work.