... the young people are the *literal* Next Generation. A group of children from the Enterprise D, maybe the very same ones whose names are on the Captain Picard Day banner in the trailer, who have grown up and tracked down the man who is a living legend to them, to be 'their Captain' one more time on whatever dangerous mission they're on. That's why the Romulan hints at him "becoming the Captain they want you to be", why Picard recalls this particilar young lady as special, perhaps in link to a Borg incident, why he says "Engage" in the particular way he does, it's a kind of 'Galaxy Quest' esque story about a reluctant hero having to live up to his reputation, tying way back to Picard's worry about 'being put on a ship in charge of children' and having to be seen as a role model as mentioned way back in TNG's pilot episode.