Dark confession time:
So, season 6 is confirmed. I sort of want 5x22 to be SPN's equivalent of "Dr. Strangelove" and Lucifer drops the bombs (or unleashes Croatoan or whatever) before any possible kicking of the bucket. Then every other episode, at least the second half of S6, is pretty much like "The End". Except maybe not quite as bad. Dean isn't some cold, apathetic hard-ass. Sam's still Sam and around. Cas isn't some tragic over-sexed and over-doped Last Man
. Dean doesn't strip the Impala, etc.
Homebase eventually becomes Camp Chautauqua and they're still driving around fighting as many demons, Croatoan zombies or whatever other nasties while the gas holds out (hence the possible likening to S1/S2). Maybe also helping Cas try to find God. All the while holding it together as this dysfunctional, but still very real sort of family and the last bastion of hope for whatever humanity remains. Also leaders for whoever willing to believe in the supernatural and fight against it. Thus, Dean, Sam and Cas as the leaders of this small (but growing) band of human survivors. With the old religions fading and dying with the old world, here are also the first seeds planted for the future of the Winchester Gospel.
SPN gives us the post-apocalyptic story, even if they couldn't (or wouldn't) give us Apocalypse every ep.
But then I remember they have no monies and they can't do that. *sighs*