That doesn't mean that Dean's role isn't to prevent Sammy from going all-out Antichrist Superstar, because that would make general sense. How else would Dean resolve the problem of the angelic civil war and the Lilith's demonic horde? Dean doesn't have the power, but Sam might. Dean, though, might have the control than Sam lacks. Which would mean that only together can the Brothers Winchester save the world.
Even if that's true, it wonÃ¢â¬â¢t stop Dean from feeling horribly responsible. His role in the breaking of the very first seal makes sense of his central role in the current conflict, Knowing that he broke, when his father didn't, will strike him right at the heart of his daddy issues. It's going to be a tough road for Dean, and that's after wondering if he could take much more as it was.
Sam, on the other hand, is sliding even further into the abyss, and it's clear that Ruby is getting exactly what she wants out of the deal. I had wondered if sleeping with Ruby was part of the process of increasing Sam's power. Apparently not, but one can't deny that Ruby's method of enticing Sam with the bloodletting wasn't sexual in context. I still think she intends to convince Sam to take down Lilith and take the throne himself, even if it doesn't involve unleashing Lucifer. Dean's role, I believe, will be to prevent that from happening.
The past two episodes mark the end of the complication phase for the season arc and the beginning of the resolution phase. Mysteries are being revealed, conflicts are clarifying, and the story is getting darker by the minute. It's sad to see Pamela and Uriel go, but it feels like those recent casualties are only the beginning.