Is this Sigourney Weaver's replacement in the Alien prequels?

Is this Sigourney Weaver's replacement in the Alien prequels?

Gemma Arterton told the Sunday Times that she's scheduled to talk to director Ridley Scott about starring in the two Alien prequels he's working on. (You may know Gemma from her role as "Strawberry Fields" in the James Bond movie Quantum of Solace.)
We don't know much about the movies other than Scott's said they'll "be really tough, really nasty. It's the dark side of the moon. We are talking about gods and engineers. Engineers of space. And were the aliens designed as a form of biological warfare? Or biology that would go in and clean up a planet?"
Presumably that means a tough, capable star along the lines of Sigourney Weaver's iconic character Ellen Ripley. It was reportedly Gemma's role in the film The Disappearance of Alice Creed that attracted Scott's interest.