That depends very much on how technology progresses during coming decades. If we get something like AGI, then having less working age people may be a good thing

That depends very much on how technology progresses during coming decades. If we get something like AGI, then having less working age people may be a good thing, because there will be much, much less demand for white collar workers at least. In the mid 2000's when I was a kid, at school I was taught that there would be a HUGE labour shortage once certain large generations retire, as younger generations are much smaller. Guess what, they retired a decade ago, and yet my country has the second highest unemployment rate in EU, with a very weak job market for fresh graduates in particular. Increased efficiency & automation ate all those jobs, nobody was hired to replace many of the boomers who retired. I doubt the future will be any different.