For those of you still complaining that this episode is going to be too packed to complete many of the Book 3 arcs properly, keep in mind, we do get like an extra 15 minutes out of the finale episode (or maybe more like 10 i guess)
I think we can effectively get a Satisfying conclusion (as in who we need to spend the most time with) to Jon, Arya and Tyrion in this time (obviously these include characters specific to those arcs as well, including Sam, The Hound, and the Lannisters respectively). Brienne and Dany just need to be moved in the right direction so we wont need to spend a lot of time with either of them. Bran's arc is an interesting one considering how swifty it is moving and might need a lot of time to effectively explain whats going on before cutting out and that leaves Theon, which i don't think we need a lot of time to spend. Have ramsey kill Balon (or better yet force Theon to push him off a bridge) and i think you have a satsifying end to his arc. Also, I think Sansa's arc is done. I don't expect to see her in the finale.
Whos missing?
Stoneheart can easily be teased in the last 30 seconds or so. Could even be as simple as Dondarrion coming across her rotting body in a river. Stoneheart's Reveal could theoretically be a big moment in the ending of Episode 1 next season.