Apparently Jaime will have two things going on this season. First is that he will believe and trust Tyrion, and apparently try to help him get through the trial. Second is that he is trying to train up his other sword arm, and recruits Bronn to help him (replacing Ser Ilyn from the books, as the actor has left to the show due to being diagnosed with a terminal disease). There's also likely a few more scenes with Tywin, Cersei and Brienne along the way. Compared to his road trip in Season 3, it might not seem like much, but enough to keep him ticking over.

Cersei's going to spend most of the season demanding vengeance against Tyrion and we might see the beginnings of her going off the rails.