Empire did a recent interview with AvP director Paul Anderson and answers a few things about the film, particularly why the alien life cycle was speeded up. He also makes it clear that he won’t be involved in any potential Alien/Predator sequels because he made AvP to re-ignite interest in the two franchises.
“I’m not attached to any sequel. I never really made the movie with the intention of making a sequel. I wanted to do it as a stand-alone film that could hopefully succeed in its own terms, but also re-energise both franchises. So that Fox could go: “Well, that made a lot of money! If you want to see Predators and Aliens again let’s make a Predator 3, let’s make an Alien 5.” The PredAlien was in the movie because it’s a really cool creature from the comic books and I felt it had to be in the film. I really wanted to see it.”