Colbert on Monday revealed that the film will be based on “Fogs on the Barrow-downs,” the eighth chapter of The Fellowship of the Ring, where Hobbits are trapped by a Barrow-wight in an unnatural fog. The story also includes a fan favorite character omitted from the previous films, Tom Bombadil. The movie will be derived from chapters three through eight of Tolkien’s landmark book.
It looks like that’s the case!
At the very least this demonstrates some deliberation and intent behind the project.