Some countries could also start getting family planning under control and ave no more people than they cna sustain.
Save your money people, so you can buy real meat as opposed to the bugs, spiders, crickets and mealworms we'll be eating in the future.
This is just kicking the can down the road. We could all eat the bare minimum calories to survive from grass if we took some enzyme supplements or something, and then we could have loads more people on Earth, but that sucks.
We need to have fewer people.
No, we don't need a larger (or even equal size) younger generation to support old people, we have robots that can do the work. The trick is to direct the profits of the robots towards the people they replace, not to the already rich who bought the patents to the robots. I mean, that is the goal with robots, isn't it? To have everyone not wanting for anything while robots look after us, with people being educated to a level they can advance society further that way.