I remember reading an interview with Scott where the filmmaker expressed interest in making a prequel that would explore the origins of the space jockey and the Aliens. At one point James Cameron was working on an origin story for a fifth Alien film, but abandoned the development when Aliens vs. Predator was announced. Sigourney Weaver has publicly expressed interest in doing a sequel, but it wouldn’t make sense to include her character in an origin story. But who knows, maybe Ridley is “toying” with some kind of reboot/prequel combo.