So it looks like the man behind the Alien franchise seems to think that the Xenomorph has run its course in terms of pop culture development. This doesn't necessarily mean that the vicious extraterrestrial creature won't appear in future Alien movies, but by Scott's admission, he recognizes that the franchise has lost momentum. In a candid moment, he was even willing to admit that two of the four pre-Prometheus Alien films (we assume he's referring to Alien 3 and Alien: Resurrection) weren't good, and that Alien vs. Predator pretty much served as the death rattle for the original thesis of the franchise. Now (like a Xenomorph embryo), the franchise has evolved to allow AI characters like Michael Fassbender's David and Walter to take center stage.