The issue is how to bring in the audience. First the studio wonders how if humans aren't in the movie, as someone we can root for. Otherwise, it could just (and literally) be aliens vs. predator. Hunters like to hunt prey in their natural habitats, also, and a movie with a predator on a safari to the alien homeworld (which Ridley wanted to do in an Alien 5 I understand) could be great. Then there would be no limits to what they two species could do. If humans are involved, then the future will be much better still, but then I've heard there are more expenses, and we need more background on what humans are doing at that time, who the predators are in the galaxy, etc.. They could do it with a lone craft out in space, which has its navigational systems compromised while the crew is in stasis, and they wake up in distant space, as "honored guests" of a predator tribe living on a remote moon or planet relative to the location of their own home world(s). That sounds like a good idea to me, actually...
