Someone hasn't been paying attention to demographics over time; first-world nations have negative birth rates (I think that's the term; replacement rates lower than 1:1). Third-world nations that get a boost in living conditions have slowing birth rates (usually takes a generation and change for birth rate reduction to catch up with infant mortality reduction, iirc). America and Canada and suchlike have population growth primarily from immigration, but they need to keep importing immigrants because the children of immigrants have the same first-world negative birth rates.
IOW, first world societies don't, really, have to understand what to do with jobless masses. They're going to lack masses to be jobless with. They might have to be concerned with losing culture wars against populous third-world (or recently post-third-world) nations, but "how do we pay for old age pensions when our workforce is 3/4 the size it used to be and retirees are twice as common?" is more likely to be a problem than "oh man what do we do with all these workers." Demographically speaking, that is.