I don't think declining population will change much, it's not going to be uniform. The remote villages/cities where all the kids leave as soon as possible will

I don't think declining population will change much, it's not going to be uniform. The remote villages/cities where all the kids leave as soon as possible will disappear once their ageing population die out. What's left of those villages will keep on migrating to the big cities, potentially even making the problem worse.