I've seen a lot of posts mainly on tumblr about this. It's mostly people saying they hope that Gabriel and/or Balthazar escaped. I think I also remember a few about Azazel and Lilith.

I think my main problem with this - other than it seems to contradict canon - is that it means that there really is no dead for good on the show. Everyone ends up somewhere with a door you can open if you're just stubborn enough.