1) I definitely agree with Johnzo that Bran was trying to lure the Night King out. Nothing else I've read really makes sense.
2) The Hound definitely has more to his story. Similar to Jamie, the redemption is one part but dealing with an evil sibling is the other.
3) I dont think she goes north as she doesn't know what would be waiting for her. If the dead won, they would have an even bigger army than before so leaving the safety of kings landing to rush in, is probably not the best move.
4) Most of the characters left still have some story left because until late last season, their goal was kings landing so now they get back to it.
My biggest issues was that we never really got to see the night king fight. His white walkers were pretty useless in the end too except for handing him spears to throw. Hell Sam took one out so they weren't all that different from their wights.