When Neill Blomkamp released art that he had put together for an Alien project that he wanted to work on, it was quickly greenlit, then put on the back burner when Ridley Scott announced his own Alienverse film, Alien: Covenant. According to Sigourney Weaver, Blomkamp might still get to make his film.
Everyone has sort of assumed that Blomkamp's film would just be quietly shuffled off while Scott produces his own film. Given the decidedly mixed reaction that the first Prometheus got, it makes sense that Fox might be a bit cautious about greenlighting two films (even though that might be a good thing for them to do).
Sigourney Weaver, speaking at an event recently, noted that she really loved the script, and that they're still hoping to do something with it:
Well, I *think* it is. Ridley asked Neill NOT to make our Alien until after Prometheus 2. He (Ridley) wanted his movie to shoot and be released first. But it's an AMAZING script, and Neill and I are REALLY excited about doing it. We're doing other things until we can get going on that. I'd be really surprised if we DIDN'T do it, because it's such a great script, and we love working together. So, it's just going to take a little bit longer to get out to you, but it will be worth the wait.
I'm wondering what else they have been working on: Blomkamp has been attached to a time travel film called The Gone World, although there hasn't been any connection about Weaver being attached. Hopefully, we'll get to see his take on Alien before too much longer.