But the fallacy of predicting future trends based on snapshot trends has been illustrated before. I think it was called the Malthusian catastrophe or something like that. I’ll have to look it up, but the long and short of it is that continued indefinite geometric population growth was as unlikely in the 1800s as would be indefinite geometric population decline now, notwithstanding current trends.
Of course, I could be wrong.
The Data for declining Japanese fertility rates is more than a snapshot. It has been decades. Plus this is not an economic problem or a resource problem. It is a sociological/political one.
Japan is pretty much out of carrots to increase fertility rates.
It needs to use sticks.
That would need a break with its current post-war liberal-democratic traditions.
Of course it could enter a brave new world and the central government can manufacture people in the future I suppose. I would argue that “Japan” would be finished and something new has arisen.