Good call on Crowley dying. That does seem likely, given Cain's prediction. I hope it doesn't, though, because I'm fond of the character, even if his story arc this season has been exhaustingly boring. I love the idea of Crowley and his manipulative mother playing mind games with each other, but Rowena is so purely cartoonish that I can't take their interactions seriously, and Crowley looks like a fool for not killing her. Besides, if they were going to get rid of him, I'd far rather they'd replaced him with Abaddon. An alternate character arc occurs to me, though: Crowley doesn't die, but comes to feel hurt and betrayed by the Winchesters, and goes into 'scorned lover' mode, reverting to a more genuinely dangerous and interesting sort of villainy, represented in part by him killing his mother.

I agree that Cas won't actually die. I honestly don't think he'll turn human either--they already did that at the beginning of s9, and it was pretty obvious that the writers didn't know what to do with that plot line, and were eager to dump it. At the beginning of the season it was set up that Metatron has access to Castiel's grace, and that he'd consider making some sort of deal to give it back. I think whatever happens with Cas will have to turn on that somehow. Maybe Dean hurts Castiel to the degree that only his own grace can restore him, and someone (Sam? Hannah?) makes a skeevy deal with Metatron to save Cas's life.