Well, it's an even-numbered season. So far all of those ended with soem great evil getting free, so I guess they won't be able to shut Hell's gates... or they will, but the Cage will open. And the boys will be out for a bit of revenge. I'd basically sell my soul for a corrupted, insane Michael. He wasn't given enough screen time and having him gone dark side would be really interesting.

I really hope Samandriel survives and we don't have to watch another torture session. Cas should rescue him.