Why is it a crisis for populations to decline to levels of the first half of the 20th century? The world worked just fine back then with that number of people.
There are problems that arise from a population that contains a lot of old people, but that's a problem that fixes itself in a few decades, and balance will be restored.
There are problems that arise from a population that contains a lot of old people, but that's a problem that fixes itself in a few decades, and balance will be restored.
Pick one crisis: no jobs, or no people.