Book 5 will be all about Hoid. Just following him around as he, like, insults Highprinces and dances on graves. While he does that, there will also be the serious side, where he(I refuse to say the name of our powerful and merciless ruler) will kill just about everyone. then revive Kaladin, since its his whole arc, and make it so Shallan or Adolin dies PERMANENTLY, and then we'll see the other grieving, and share a closer bond with Kaladin. Also, my prediction is that Elhokar will spend the entire book learning how to be a king, or a leader, while Kaladin teaches him and constantly shifts from "stormridden king" to "OMG he is like, so CUTE" or something like that.
Also, Odium might come, but he'll be unable to focus his efforts on Roshar because of something that "requires his attention". Just seems like his way of doing things.