Ridley Scott has already confirmed that a Prometheus sequel will be his next project, as soon as he's done with publicity for The Martian. However, it now sounds like this might only be the beginning, with the director suggesting that there could be as many as three more sequels before the story is finished.
"Yes," replied Scott when asked by German outlet FilmFutter whether the franchise will directly link up with the Alien series, "but it won’t be in the next one. It will be in the one after this one or maybe even a fourth film before we get back into the Alien franchise."
"The whole point of it is to explain the Alien franchise and to explain the how and why of the creation of the Alien itself. I always thought of the Alien as kind of a piece of bacterial warfare. I always thought that that original ship, which I call the Croissant, was a battleship, holding these biomechanoid creatures that were all about destruction."
Whether or not those plans would interfere with Fox’s proposed Alien 5 remains to be seen, although it has been suggested that the advent of Prometheus 2 might have already delayed the project. Prometheus 2 will begin filming in February with the returning Michael Fassbender and Noomi Rapace, and a release date yet to be confirmed.