The Maze Runner: The Death Cure ending closes the trilogy with the survivors on a safe island, Teresa and Newt both dead, and a note that tells Thomas what to do next. In my opinion, the film chooses grief over spectacle in its last minutes, and that choice is what makes the finale land.
Here is what the ending settles. The survivors escape the collapsing WCKD headquarters by Berg after the cure has been taken from Thomas's blood. Teresa dies in the fall, and Newt had already died by his own hand. The group settles on an island away from the Flare and WCKD, and Thomas reads Newt's note asking him to look after the others.
So, was a cure found? As the film presents it, the means of making one was obtained: Teresa removed Thomas's blood on the roof so that it could be used, which is the thing WCKD had been chasing through its research on Immune young people. It could be argued that the film cares less about the medical result than about the people left standing, since the closing beat is Newt's note and not a demonstration of the cure.
The ending also completes arcs that began earlier. In maze runner the scorch trials, Thomas learned that the facility belonged to WCKD and that Ava Paige was still alive. Here, Janson kills her, and the Cranks that Thomas lets loose then kill Janson, so the people who ran the experiments do not outlive the building.
Teresa is the most debatable piece. The film gives her the act that makes the cure possible and then removes her in the same sequence, and, perhaps, that pairing is why her arc carries weight even for viewers who never warmed to her. Because this is the final film of the trilogy, nothing further is set up. Where the story sits in sequence is covered in the maze runner timeline, and how the three films compare is argued in maze runner movies ranked.
