This series is not just based on the one book, "Siterhood of Dune." It's based on a trilogy by Brian Herbert and Kevin J. Aderson: "Sisterhood of Dune," "Mentats of Dune," and "Navigators of Dune." I would imagine the series creators would want to explore the material in the second and third books of the trilogy since the series' intent is to flesh out the Dune Universe outlined by Frank Herbert.