If they ever do make a film about both xenomorphs and Yautja, they would have to do something like this:
Set it in the same era as "Aliens" and pit a small group of civilians in a survival situation on a space station overrun with xenomorphs, maybe as a result of the Weyland-Yutani Corporation's experiments again. At the beginning of the film, Colonial Marines could come to see why the station has stopped responding, and attempt to rescue the survivors. They would spend a lot of time fighting and running away from Aliens. After approximately halfway through the film, a Predator would be revealed and shown to also be hunting the Aliens. It would periodically appear and take out a marine or an alien, acting as both antagonist and saviour to the human civilians, but remaining in the background of the film like an unknown, abstract threat, compared to the constant, unrelenting threat of the Alien swarm. Near the end, all but one of the colonial marines would be dead, and maybe a one or two of the civilians would also have died. They would be faced with an Alien Queen, but, with no airlock in sight, the remaining Marine would be forced to heroically fight her. After wounding her and fighting bravely, he would be killed, but then the Predator would arrive to finish off the Queen. It would then take her head, regard the civilians but leave them alone because they are unarmed, and leave the ship.