Neill Blomkamp's original plan for Alien 5 was not actually going to feature the Ellen Ripley character. Nor was it originally meant to act as a continuation of James Cameron's Aliens. It was not until Neill spoke with Sigourney Weaver on the set of Chappie did they decide to revisit the Ripley narrative once again. Speaking with YouTubers Funhaus, Neill Blomkamp touched on Alien 5's original plans while speaking about his latest venture, Oats Studios:
I basically worked on Alien for about…I met Sigourney on Chappie and I had a different idea for an Alien film I wanted to make. So I had this idea for a story set in the world of those two first films that was not a continuation of James Cameron’s. It was just in the world of it and it had a totally different character that was the lead character. Because my assumption was that Sigourney would just never make another one and I told her about it on Chappie and she was like “No, no, no! I actually would make another one because I felt like Ripley’s story didn’t end correctly.” I was like “oh, okay. That’s amazing!”
So I went back to Vancouver and while I was editing Chappie I started to think about what I would do with Sigourney as basically a sequel to James Cameron’s film. I spent about a year working on it with only Sigourney knowing and I hired one really awesome concept artist. We put together essentially a script and all the artwork and that’s what I went to 20th Century Fox with. They seemed really into it and Ridley came on as producer and then it just unraveled.
Thanks to AvPGalaxy for the heads up.
Now, despite Neill's remarks about him feeling like Alien 5 is completely dead, sources close to Fox have provided us with information which seems to suggest that Fox have not given up on Alien 5. Throughout Alien: Covenant's marketing run the topic of Alien 5 kept surfacing and of course Ridley and company were more focused on the Prometheus sequel than Blomkamp's side story within the franchise. But we can confirm through multiple trusted sources that Alien 5 is not as dead as everyone is assuming it to be. It's merely in hypersleep until MUTHUR wakes it up...