So even given that this thing is going to be 66 minutes, I'm struggling to imagine how they're going to fit everything in. I was trying to tally up all the running plotlines, and we have:
1. Bran and his magic tree stuff
2. Jon Snow going north of the Wall to meet Mance
3. the Boltons and Reek doing their thing, plus the Ironborn generally failing at things
4. Littlefinger and Sansa being all schemy
5. something involving Arya, the Hound and Brienne
6. Tyrion's trial stuff, plus Tommen and Margaery
7. the Mannis preparing to implement his Plannis
8. Dany continuing to be boring over in Essos, with Jorah the Explorer possibly becoming a divergent subplot
9. probably something else that I'm forgetting, plus Gendry's continuing attempt to set a world record in endurance rowing
Now we know from the preview and/or can reasonably anticipate that the Bran, Wall and Tyrion plotlines will be significantly developed, and that the Arya and Dany plotlines will at least be touched upon. Now despite the appearance of Dany and her dragons in the trailer, I have a strong suspicion that nothing really exciting is going to take place with her, and that we're probably just going to get a hint at things yet to come - and that Jorah probably won't appear at all. Regarding Arya, people online have deduced from a preview shot that she'll be meeting Brienne. But this has me perplexed: why does she still appear to be wandering the countryside with the Hound? Why won't she be going up to the Eyrie and reuniting with Sansa? Do the guards reject them as liars or something? (I guess a Stark reunion of any kind is too good to be true.) In any case, I fear that Brienne may not be received as warmly by Arya as she might like.
Regarding the Wall, I suppose what will happen is that Jon Snow will work out some sort of agreement with Mance whereby they'll cooperate against the White Walker threat. (I greatly doubt that we're going to see any more combat on the Wall itself – I mean, they couldn't top what they did in the last episode.) But at the same time, I expect that it won't turn out as I expect, because that seems too simplistic. Jon Snow's departure from the gate and fade to white do seem to portend exciting things. But I think Jon Snow has plot armor for some time to come: we still have to resolve the mystery of his parentage, and I strongly suspect (based on no evidence at all) that some interaction between him and Dany will play a part in the conclusion of the series. I mean, he brings the Ice and she brings the Fire, right? Unless the Walkers bring the ice, in which case he just brings glumness and amazing hair.
Regarding Tyrion, I think his plot armor is severely dented but still holding. Call me naive, but on an intuitive level I don't see him dying. Even this show is not free from convention, and the way things were set up ("I sentence you to death!" – cut to Tyrion looking shocked! – end episode! – wait two weeks to find out!) just screams to me that the sentence isn't going to be carried out. On the other hand, I think some blood will be shed in King's Landing. I recently heard a stimulating piece of speculation from a fellow non-reader: maybe Jaime will intentionally get himself killed while saving Tyrion. At that point, Tywin – who values House Lannister over everything – couldn't kill off his one remaining son no matter how much he wanted to. Honestly, based on Jaime's character arc this season, his death feels more plausible to me than Tyrion's. His growing sense of moral conflict and alienation from the family seem to me like harbingers of tragedy, similar to the way in which Ygritte was torn between her people and Jon Snow. And what an awesome death scene he could have! But for gods' sake, if you've read the books, don't give me even the slightest hint of whether or not this is what happens. (What seems almost 100% certain to me is that some major character will die.)
Regarding the Prince With the Promissory Note, I really want to see him do something, but I have this nagging fear that he may not appear in the next episode at all. Guh, when is somebody not married to or descended from a Lannister going to rule this place?! Regarding the Boltons and Reek, I strongly suspect that they won't appear – the legitimization scene seemed like a decent wrap for them for the season. The most recent scenes with Littlefinger and Sansa also seemed good to end the season, so I suspect that they won't appear either. On the other hand, I expect that someone I'm not expecting to appear probably will appear.
Regarding Bran, no clue.
So anyway, I'm anxious to see how they fit so much stuff into one episode. What's encouraging is that the finale is the one episode from this season that they're submitting for the writing Emmy. So it has to be good, right? D&D are saying it's the best finale yet, although you'd hardly expect them not to say that.