"Then we're already done for, Crowley. We pack up and we leave and we try to outrun her." But he doesn't see how that would be any use at all, and then they'd spend their last moments alive trying to escape the inevitable. Scared, tortured, but with each other til the bitter end, at least.

"But I'll know we tried our best to do the right thing. And we saved this Earth, and they'll be prepared for when Heaven and Hell return. And that's all we could hope for." He smiles weakly, and buries his face into Crowley's chest.