While we know that Ridley Scott has a dual role planned for Michael Fassbender in Alien: Covenant, and that Katherine Waterston is one of the new additions to the cast, less certain has been the state of Noomi Rapace's role as Elizabeth Shaw. He's said in the past that Rapace would be back, albeit in a much smaller role, but it appears that is no longer the case, either.
Baz Bamigboye chatted with Scott and asked him specifically about Rapace's return, to which the director confirmed she would not be back. He then added, "We’re still casting the main roles", suggesting that maybe the Shaw character is being recast and not totally wiped off the board. The story takes place years after Prometheus and follows a new crew that discovers the android David on what appears to be an uncharted paradise, and perhaps Scott felt there was no room in the story for Shaw. Hopefully we'll get some explanation as to her whereabouts.
Alien: Covenant opens October 6th 2017.