What is the threat?

I think the main threat will consist of one or more of the crew members becoming infected with some mutation of sorts and than attacking the rest of the crew. Also the Space Jockey's I think will become a partial threat in the film. If there are any xenomorphs they are bound to look entirely different and be a deadly threat. So my guess is those 3 things. 1. crew members will become infected with some mutation that changes who they are and they will begin to search and destroy any remaining crewmen. 2. Space Jockey's will unleash some kind of bio-weapon, whether it be xenomorphs or another kind of species. 3. The bio-weapon itself will potentially not only harm the human crew but also the Space Jockey's themselves, as we are led to believe in the beginning of "Alien" when Dallas, Lambert and Kane find the Space Jockey dead with its chest burst open.