Yeah, I kind of wonder if they intended to address prophet lore. We've long speculated that Chuck was God, but maybe not. Maybe prophets are nephilim -- half angel, half human? I don't know, but it might have been interesting to find out. I mean, why shouldn't they be angelic -- the reapers are now. *sigh*

I agree though that I don't want them to bring Kevin back. Death has certainly begun to lose it's sting with the way that they keep bringing Bobby and Castiel back. I get that Cas is an angel but still, and Bobby hasn't been "alive" but just being present in some way undermines the "finality" of death and Sam and Dean's uniqueness as you say.