All four Pevensies are in the last book. Their age is irrelevant. Knowing the storyline in the last book of the series the statement about "aging out" makes no sense. The train station is heavily symbolic, and the last book will blow regulation psuedo Christian Dominists' minds. The last chapter absolutely runs counter to the "Christian culture" worldview. It's a subtle book. I'm not sure it can be made into a film.

I think the reviewer would have benefitted from having actually read the full series (or re-resding, because some stuff is clearly forgotten). I won't reveal the end of the last book, but it counters the assumptions of the future of the series from the review.