I don't claim to know how the rest of this season, or the show in general, will play out, but i have a theory for what would make an awesome show.
Seeing as it is obvious that Ruby is far more than she appears, it'd be nice to see her show her full potential. From what we know about her, she helps Sam and Dean because "she remembers what it's like to be Human", but I'm with Dean in the not trusting department, after all "she's a demon!". While Ruby may not end up being the top dog in the demon hierarchy, it's more than likely she is pretty sinister. And i know, she's helping out, blah blah blah, but what's her end game? What does she get out of this. Let's take a look at the things that don't quite make sense considering Ruby's "paygrade" as it were.
1. She knows how to fix the colt?
2. She has a demon killing knife?
3. She is allowed topside again after Lillith banishes her to the corners of Hell, and she supposedly "convinces Lillith" to let her have another chance.
For the not so strong demon she claims to be, Ruby has a ton of power, and it seems more and more likely she is near the top of the plan for the Demons to bring Sam to the "Dark side". Ruby is bad news, and time will show it.
Now on to the Sam/Dean showdown we all know is coming, once Sam is completely off the reservation that is. The thing is, even if Sam were pure evil, how are they going to get Dean to turn on Sam? No matter what, Dean will try to save him, because he's just that kind of brother. He never says never. The apocalypse brings the armies of heaven (good) against the armies of hell (bad), and it just seems likely that John Winchester will be fighting on that Good side. "He's made of the stuff of Heroes," after all.
Biblically speaking, Humans, after all is said and done, take a position higher up than angels in hierarchical positions, so its not to out there for the writers to bring John back with some epic powers during the final fight between Heaven and Hell, and this is how I see it playing out.
John comes back, and fights his lost and now evil son Sam, who is right where the demons (Azazel) wanted him the whole time, leading the evil demon army. With the powers he has, Sam ends up killing John in Battle, and it is this action that gives Dean the anger, strength and courage to do what must be done and stop Sam. Only something like Sam killing his father would prompt Dean to give up on saving Sam, and like Castiel said "The Righteous Man who begins it is the only one who can end it."
And that's how i see it playing out (as of now).
What are your thoughts?