The Alien cinematic universe may be getting quite a bit bigger as it sounds like Ridley Scott is thinking of three sequels to Prometheus. These would be part of the Prometheus series and not the planned Alien 5.
Scott explained his plans to German film site Film Futter about when the Prometheus series will explain the origins of the 1979 original:
“Yes, but it will not be the next. It will be in the one after the next Prometheus or perhaps even in a later one, before we are in a sense back in the Alien franchise.”
“The whole point is to explain the Alien franchise and the how and why of the creation of the aliens. I always saw the Alien as a type of biological warfare. For me, the original spaceship that I call the Croissant, is a warship that contains these biomechanoids creatures that are all about destruction.”
As long as the series actually gets to that point, and we get a true Alien prequel, I’ll be there for the sequels.