ehmm woud be save to say that the new crew will be the crew from Alien 5,
Hicks and Ripley head to their homeworld and so is Shaw and David face.
therefor Ridley calls it Alien: Paradise Lost, if he had called it Prometheus 2 he wouldnt have the right to use the characters like Hicks and Ripley and calling it Alien he can choose by himself to use the characters Shaw and David.
But maybe Ridley was a little off and did he just mentioned Blomkamps title for the new Alien movie LoL