Supernatural fans - Do you think they is redemption for Castiel?

I want to believe Castiel can still become good again. After all in
Season 5 when he beaten Dean he chose to knock him out rather than
beat him until he is out cold. I think Castiel is just angry at Sam
and Dean that they turned their backs on him when he needed them most
but I still think he can be good again,
Your views? Can he come back