I actually have only one short thing to say. Well, two short things. I have been massively annoyed by Crowley's storyline all year, but when Dean asked Sam, Cas, and Crowley to take care of whatever came out of the barn, and Crowley was the only one to say yes, that look Dean gave him was great. It's odd to think that Crowley is someone that Dean can count on, but I think in this case, it's true, and it was a good example of why you need a diverse set of allies.
The other thing I have to say is that they've set up a very interesting conundrum for Dean. I mean, we already know that his love for Sam is strong enough to save the world, to tell the heavenly host to their face to screw it, and to tell destiny to suck it. But at the same time, we know Dean has had what we might call self-esteem issues his whole life. He doesn't think he himself is worth saving. So the question is, is Dean's love for Sam strong enough to save himself? Because that's what it's going to take to get out of this intact.
I really wish I had time in the next month to write this up properly, but what I would love to see from the rest of this season is Dean fighting off the pull of the Blade (but of course getting his hands on it again for some reason), and Sam realizing through research (or maybe Dean actually telling him what Cain said) that the only way to remove the mark is to go back to the source, to use the Blade to commit fratricide, and then Sam willingly sacrificing himself to Dean so that the Mark will disappear. And then Death saying, "Sorry, Sam, your ten-ride ticket hasn't been used up yet," and Sam coming back to life and everyone moving on to S11. Think of all the delicious angst.
(Also, I really want a hunt where Dean gets fatally wounded except not, because nothing can kill him but the Blade, because the relief/horror of that moment would really be something to see on their faces.)