It's a paradox I tell you. It just covered 2 movies in one. What on earth could come next?
Predators hunting americans/nazis in WW2, with them having a key role in the outcome of the war. This could also be a nice way to re-change the designs to a more tribal/vintage style.
Predators hunting in Vietnam
Predators hunting ancient warriors in Egypt
Predators hunting pirates (P2 flintlock)
Even with Stargazer i think there are really cool ways to tell a new story without the Predator killer, more focused on an actual team capturing a Predator by surprise during a hunt... with them getting to the Predator spaceship, which then flies back home, there they have to face and fight different Alien species with the last survivor and biggest warrior being worthy enough to fight against an elder Predator.
The core story is always a hunt, and with that there are endless possibilities for really good movies, even on a smaller scale action/horror.