As you look at Wendy, you may see her hair becoming white, and her figure little again, for all this happened long ago. Jane is now a common grown-up, with a daughter called Margaret; and every spring cleaning time, except when he forgets, Peter comes for Margaret and takes her to the Neverland, where she tells him stories about himself, to which he listens eagerly. When Margaret grows up she will have a daughter, who is to be Peter’s mother in turn; and thus it will go on, so long as children are gay and innocent and heartless.

J. M. Barrie (1860-1937) Scottish novelist and dramatist [James Matthew Barrie]

Peter and Wendy, ch. 17 “When Wendy Grew Up” (1911)
    (Source)

Final lines of the novel.

Barrie's novelization of the play Peter Pan (1904, but first published 1928) incorporated a coda to the story from his 1908 sequel, When Wendy Grew Up, An Afterthought, which had this line, Wendy speaking to Nana:

WENDY: This is how I planned it if he ever came back. Every Spring Cleaning, except when he forgets, I'll let Jane fly away with him to the darling Never Never Land, and when she grows up I hope she will have a little daughter, who will fly away with him in turn – and in this way may I go on for ever and ever, dear Nana, so long as children are young and innocent.