I think that once the boys have calm down they can work through this. Cas is still protecting them, as I expected. Cas knows what he's doing is wrong. Its the same way with Sam in season 4. Unfortunately this time around you don't have a way of contacting Cas to talk this out. Balthazaar's not a good candidate. Thats why I really wanted Rachel to survive.
Dean is only open emotionally to family Sam, Bobby and now Cas. It shows that he is like family to Dean.
I wonder if the Titanic thing was a way of Cas getting out of his deal with Crowley for the 50G loan. Pay him back as it were.
Anyone else wonder why Eve is still laying eggs and what those eggs are for?
They can't kill Cas yet. I mean if Cas goes down the Apocalypse is back on. I'm sure that once the Raph is stopped and there will no longer be any Apocalypse Cas will willingly take whatever punishment God wants to deal on him.
Scriptwise I think Cas may have to be written off. I think I've said it before Cas is like the ultimate ex dues machina. One of the boys die Cas can bring him back They need to time travel Cas can swing it. They need to take care of an enemy threat Cas comes in to save the day. Don't get me wrong I love the guy. I just don't see how they can keep Cas stunted.
Hopefully Cas' reward/punishment for his acts is for his grace to be taken away at least he isn't dead that way Mischa can still be in the story.
I would love to see him get his own show where he's all but human and relies on his knowledge and rituals to help people and earn his redemption.