https://en.m.wikipedia.org/wiki/Demographics_of_India
Bluntly, whether you meant to or not, this comment is full of coded bigotry. It invokes images of a foreign hoard, bang at the walls of the west, threatening to dilute or destroy "our" way of life.
2. It is not full of "coded bigotry." These are simple fact that almost everyone agrees on. India has explicitly made it a goal to reduce their fertility rate over the past few decades because of the problems of overpopulation. China's economy absolutely benefits from a high population. And yet I doubt you would characterize their humans rights record as stellar. It does not mean that Indians or Chinese people are in any way inferior to Westerners. And I highly doubt that the OP would agree with that either.
3. Even if it was, that isn't a critique of the comment's argument. It just means you find it distasteful. So what?
Yes, it is.
The core of their comment is "oh noes western values will be lost!" (Or as they put it: "the global West has values worth preserving for the future").
My point is, no, they won't, because fertility is dropping everywhere. We're not that special. And that this purported fear is simply rooted in age-old racist tropes of a loss of cultural identity to scary foreigners, nothing more.
Perhaps China and the West will both face population collapse. The argument still stands that Western values (and Chinese values) will be lost.
But humanity won't just vanish in a puff of smoke. It just means that societies that do not share "our" values will live on.
Do you believe in human rights? Feminism? Racial equality? Well too bad, because, at the current going rate, very few people in the 22nd century will.
Baloney. The comment might rely on some outdated information, or if you want to be uncharitable, outdated stereotypes, but that isn't bigotry. There's no need to moralize.