In a recent interview with Total Film, Ridley Scott was asked what he thought of the Alien Legacy as a whole. He replied:
"Things have certainly come a long way since Alien. I think he has been seen too much in the other movies and he's not scary anymore. Though saying that I have enjoyed all of the other movies and I think it's a very successful and important series.
He was then asked if he would consider making a fith and final chapter to series.
"I'd only do that if they had a good script. The story is the single most important thing when making a movie. I would certainly enjoy working with Sigorney and the Alien again though...