We are in uncharted territory on demographics and what it is going to mean around the world. It's different issues in different countries but there are an awful lot of places that are completely screwed. At least in Japan and South Korea they have made some smart choices in allying with the US from a trade and military perspective to an almost submissive level and they have embraced AI and robotics to increase productivity. Neither country allows any significant immigration and since they aren't having babies that's going to get very interesting.
China and Russia are the most screwed because they not only have horrific demographics (likely worse than S Korea but they don't give out accurate data) but they have done very little to prepare for it. That's why they are so dangerous, dying powers looking for a lifeline do irrational things.
Western Europe is on a slower paced death spiral but the failure is still inevitable. Israel's numbers look good until you realize that many of the births are Arabs and not Jews. The US is in decent shape in part because we still are the brain drain for the 1st World. People focus on the illegal immigration (and rightly so) but we also have been getting the best and brightest from all over the world for 150 years. Think of the impact of guys like Elon Musk or the legions of Engineers that come from India and China. We also get the best and brightest from Central and South America and even places like Nigeria as well as still pulling from Europe.
"The most terrifying words in the English language are: I'm from the government and I'm here to help."
Ronald Reagan