Think about all of the things he has seen, all of the worlds he has explored, all of the green women he has slept with, and when he is faced with death, it shocks even him, to the extent that all he can say is, “Oh, my.” I’m not sure how popular this scene is among the Star Trek Zeitgeist, but I imagine it’s probably hated. I, however, love it. Feel free to tell me how I’m wrong in the comments.
That line is in the film to imply the ship and crew would never age - that for the fans the original show would be timeless. It’s not so much a measure of hope, it’s more a wink and nod to the audience.
Peter Pan and his crew in Neverland never age, they remain perpetual children.
But this would give a similar message… Kirk’s adventures will never end.
They do end. That’s the point.