Even with the basic premise being repetitive, they can still inject freshness into the franchise by doing a number of things that don't necessarily change the "hunt - be hunted dynamic" of the movies.
For instance, they could show more dynamic and interactions between the Predators themselves, or between Predators and humans (Galgo and Ahab), they could give us modest insight into their culture, or their world/animals (like in Predators). It's an entire species that we honestly haven't been shown much of, save for some cool tech and what's been eluded to in the comics or novels. Sure, delving into this could potentially spoil the "mystery" for those that care, but that doesn't mean that these options don't exist to keep things interesting moving forward.