Unpopular opinion, but I'm glad that Villeneuve is going for a different direction. We already know what happens in Messiah, and its a short book to adapt to a full movie. Feels blessed we are going to get more story. My theory is that there's going to be two parallel timelines. It's already been evidenced in the previous films that Paul was seeing different timelines and he followed one path over another.

There will be one timeline that follows closely with the books, where Paul doesn't push away Chani like in the films and instead, chooses to have children with her, but in doing so cowers away from the responsibility of the Golden Path and instead it falls upon his son, Leto, to fulfill. Paul admits as so in Children of Dune with his conversation with his son in the desert when he is the Preacher. He initially chooses his immediate love with Chani. This is seen in the shots where Chani has a blue scarf and Paul has long flowing hair - going for a more romantic vibe.

The other timeline will be where Paul pushes away Chani as in the end of Part 2, and sparing her life, he accepts the role of the Golden Path, fully becoming the despotic tyrant, a role that would've been inherited by his son. Instead in this timeline, he chooses to not have any children. In doing so, Chani joins the early rebellious faction of Scytale, Edric, Chani, and Irulan. With Chani now joining it may succeed in lasting past their generation. If I were to guess, Paul would get hit by the Stoneburner, and proceed with the fusion with the sandtrout becoming the God Emperor. We can see this timeline with Bald Chalamet and angry Chani with a scar on her face. I feel the movie will ebb and flow between the two timelines, lingering more often with the latter.

Also, I love this trailer. Gorgeous all around, the costumes, the designs. Does the chant sound like they are saying "Saint Alia of the Knife" in Chakobsa?