Either way, I don't see Bobby coming back as the very much alive hunter he was before this happened. They could have done that before he went unconscious again and gone into critical condition near the end of the episode. But now we have reached the point of no return. I can't wait to see which road the show is going to take.
Crossroad deal. Dean's done it before so they know it works. It's just an issue of finding something that the demon wants enough to trade for. Obviously, souls are right out. But that's okay, because no demon wants to be stabbed to death. Sam and Dean can easily summon a crossroads demon into a devil's trap and not stabbing it to death for Bobby's life. And if it refuses, stab it to death and summon another. A pile of dead bodies can be a good motivator.
Crowley probably won't appreciate such shenanigans, but they really don't care what he thinks.