This is not as hot a topic as Global Warming but I think it will have a bigger effect on lives. The developed world is losing population. Most of the undeveloped world is approaching parity. This has all happened really fast. When I was a kid population growth was the big bugaboo. We were going to run out of land, water, resources, etc. Now if this is happening, it will change the economics of a lot of situations. Wars in the not that to distant past were fought over land. Now the whole idea of war and depleting the population of young men and women is not going to be very tempting.
10% of Japans housing is empty. There are some other factors to this but their population is in decline.
Russia is losing 1/4% of population a year.
No idea how to take advantage of this of if even possible but this is one of those trends that could change everything.
Currently with a FTR of 2.36 and a 2.33 is needed to maintain the world population so we are still expanding. But this is only because of Africa.
https://en.wikipedia.org/wiki/Total_fertility_rate
And Africa is changing fast.
https://en.wikipedia.org/wiki/Total_..._1950-2050.png
PS yeah a little slow here on X-mas eve. hahahaha