Honestly I'm not even sure they're going to do more than unceremoniously kill Thufir off in the background. But it's possible that they took the first movie as a chance to explore Arrakis, and will take the second to explore the broader galaxy and its politics, players, and philosophies.

We still haven't met the Emperor or his Daughter, the Imperial Court (beyond an emissary. No dinner party means no Fenrig and Margot), the Guild (as political players) CHOAM? (I forget if it's even mentioned). All of these could be worked in (and it seems like they will be given we see casting of Irulan at the very least), but you can imagine a version of the story that is less concerned with the broader politicking than it is with the action on Arrakis.

They also fundamentally changed the nature of Kynes' death. So it is possible they are not even interested in (or, to be kinder, that they feel they don't have time for) the planetological lifecycle of the worms and the spice. That it will serve only as a mcguffin. But that's pure speculation.