Yet another "population decline is the end of the world" bull shit article. Population decline is not a problem. Historical population declines worse than the current ones like the Black Plague and WW2 have always resulted in a better world for everyone.
When the population goes back to sustainable levels it will go back up again. It's no different than any other ecology where animals outgrow their environment's carrying capacity and decline. After declining, they grow again until the limit is reached again.
When population goes back to 1950's levels, labor will be valued like it was in the 1950's, and the average person will once again have the wealth and leisure time to have a family.
Population decline is only a problem for the ruling class who live by skimming a little profit from all workers. If there are less workers, they will have to be paid more which means less excess capital for mega yachts.