The Predator 2018 ending closes the fight with the big Predator and then opens a door with the exosuit. Once Nebraska Williams brings the ship down and Nettles is lost in the crash, Quinn and Casey Brackett finish the larger Predator. The final scene shows a lab opening cargo from the wreck and finding an exosuit built to fight Predators, and Quinn agrees to wear it.
What does that mean? In my opinion, it is a deliberate sequel hook. The suit turns Quinn from a soldier who survives an encounter into a man equipped to pursue the aliens, and that shifts the series from running and hiding to a war footing.
How does it compare with the rest of the saga? Predator 1987 is a squad of mercenaries picked off in a jungle by one hunter, and predators 2010 drops eight strangers onto a hunting planet. Both keep the humans on the back foot. Here the humans capture a Predator, lose it from a lab, and then watch a second, larger one kill the first. That is the film's real escalation, and the exosuit is the humans finally getting hardware of their own.
There is also a production reason the finale feels crowded. Fox reshot the third act after test audiences, the climax was reshot in July 2018, and Keegan-Michael Key said about three quarters of the final act was rewritten. It could be argued that this explains why the ship crash, the sacrifice of Nebraska and the exosuit reveal arrive in quick succession. Edward James Olmos also lost his scenes as General Sanchez to the runtime cut, so the government side of the story is thinner than the setup suggests. The film ran 107 minutes in the end.
It could also be argued that the hook did not land, because the story did not continue. No sequel has been announced for The Predator 2018. The next main film, predator badlands (2025), went in a different direction entirely, following a young Yautja named Dek and a synthetic named Thia, and it also ended on its own sequel hook, according to TheWrap. As of the latest reporting, no film after Badlands has been dated, as covered on the new predator movie page.