I'm glad that the factions have resolved down.
There is obvious opportunity for alliance between Dany and Jon (especially if I got the implications of the flashback right) .
I think the Lannisters are going to go one of two ways. Either Jaime is finally going to accept Cersei is nuts, take control and sue for peace (his look of disapproval would suggest so) or, I think more interestingly, Cersei will somehow ally with the White Walkers. (Perhaps The Mountain will provide an interface between the living and the dead?)
There are the Martells / Tyrells, but I think they will just ally with Dany/Jon otherwise, narratively, they're just complicating things when it should be we're setting up the board for the final showdown.
And then there's the White Walkers... seems pretty clear cut what needs to happen to them at the moment... and it involves dragon glass blades.
If there are going to be only two seasons (which rumor has it is the case). I think we'll get the resolution to uniting Westeros in the next, and then sorting out the White Walkers in the final one.