Perhaps, but you'll probably wind up with a shitty movie. Books and movies are fundamentally different media, and a story that works well in a book usually, IMO, just won't translate well to a 2-4 hour movie without making major changes to the story and plot.

However, perhaps instead of trying to make movies from books, they should make miniseries (3-10 hour-long episodes).

Because if there's anything AI currently sucks at, it's giving a reasonable summary of a larger context.

I think Book --> Movie Script is probably going to arrive before generated actors.

You're right: the current quality of film/TV scripts is terrible, so this is definitely one place where LLMs could do far, far better than most humans in the profession.

Lord of the Rings was considered unfilmable for decades. Computers made it possible.

I'm not referring to the technical aspects of filming, I'm referring to the huge differences between them as a storytelling medium. A movie only has 1.5-3 hours of screen time available to tell the complete story (unless you do something like the recent "Dune" movies, or make a trilogy like LotR), but in addition to that, a lot of things that work for books don't work the same way for movies: pacing, etc.