There definitely needs to be one or two movies where the Predator wins. It would a good decision to expand the franchise on a story-telling level and just make the point that the winners we've seen are exceptions, not rules. Potentially a Prey sequel could go there, maybe, but ya never know.
Plus, it would be nice to tell those trolls that have been meme-ing the whole "only loser Predators come to Earth" nonsense after Prey to piss off.