Please stop posting unsubstantive and/or flamebait comments to HN. You've been doing it a lot, it's not what this site is for, it destroys what it is for, and we eventually ban such accounts.

https://news.ycombinator.com/newsguidelines.html

Just having people in your country doesn't equate to economic productivity. Western nations will want highly educated young people doing hard mechanical labor that often takes two decades of training to get proficient at.

And yes, we will reap the most educated and skilled from less developed nations throughout this century. Which.. just condemns said countries to perpetual destitution. If the best and brightest you invested in leave to go to other countries you both have no incentive to invest in them in the first place or you wasted your economic surplus that is needed to progress your society towards becoming industrialized in itself.

The uneducated poor of the world are not useful to industrialized society. Its why every industrializing nation always adopts universal education to at least make capable laborers out of the poor. Its unlikely to change without world powers deciding to be way more altruistic about their economic exploitation of the poorest regions of the planet.

> Why is immigration not the answer to this?

Because of the word “global”.

Unless you are talking about interplanetary immigration.

OTOH, the real solution is “this projection of current trends into the future is likely to be just as wrong as when people were projecting the rapid rate of global population growth in the 1960s to continue without bound, or even further accelerate”.

Did you read the article? It addresses this. "However, this stops being the answer once nearly every country's population is shrinking."

or undeveloped countries become developed. - this is clearly an option.

Because of the resulting ethnic conflict: https://arxiv.org/abs/1110.1409

Perhaps the new Soviet man will be free of ethno-centrism, but until then, we have to deal with the flawed people that we have.