Everything I say here probably has occurred to nearly everyone else, but I've been in panicked fangirl mode and not thinking through things clearly, I believe.
Speculation and spoilers behind the cut.
First off, we've been told Misha will have a smaller role in the new season, they've shown us video that looks like Castiel as god goes from omnipotent to bloodied and possibly dying. And they tell us to "kiss your Cass goodbye." Seriously, who does that to a fanbase, especially if it's true and we have to accept that Castiel is gone?
I think we're being played.
I believe that Castiel as god is the new big bad and will be a thorn in the Winchester and Bobby's sides all season. This whole Butch and Sundance schtick they're throwing at us may be true up to a point, but I firmly believe that hidden arc throughout season 7 will be the redemption of Castiel. He will do bad things and some not so bad things. He knows all the boys' tricks, no one could be harder to defeat that not only an omnipotent being, but one who knows them intimately.
They will have to decide if they want to destroy him, or seek to help him. I believe that they will spend time trying to do the latter.
I don't think this is the end of Misha Collins on Supernatural. I believe we're being subjected to an elaborate game of hide and seek, one that will result in the biggest season premiere ratings Supernatural will have ever seen.
However, I still think it's important to write and tweet and have #savecastiel thursdays. The interest still needs to be shown. And we need to keep up fandom interest.
These are only my thoughts and not terribly profound ones, lol, but I feel better about the whole thing now. Seriously, I want to look forward to September!