Maybe Cas is still in there to get control of the Leviathan. It could be played out a lot like Swan Song with Cas jumping into purgatory with the Leviathan on board. That's pretty close to been there, done that so I hope it gets wrapped up a different way. I won't believe Cas's dead until I see the black wings.
Here's some good stuff
Slow Ride is such an ironic song for the Road So Far
New exploding ectoplasm title card with the dripping goo
Dean's red plaid shirt of angst and the overshirt from the I Wuv Hugs scene
Dean's printed T-shirts calling back to earlier seasons
Dean repairing his car is always awesome
Crowley in the trailer park
Crowley's expression while he waits to be smited
Crowley, Crowley, Crowley
Death, Death, Death - everything about that whole scene
Sam not giving up on Cas and putting up with Dean
Nick!Lucifer, so cool to see him, I was completely surprised
Here's some stuff I hope gets worked into further episodes
Dean's spiral of depression
Dean's drinking (he was drinking in four of the scenes he was in)
Sam's PTSD
More Crowley, Nick and Death
Some sort of decent resolution for Cas
I hope Dean, Sam, Bobby and Cas survive the season and go on for more. Is it Friday yet?