Personally, I think the real solution, the ultimate solution, was detailed in the 1930s book "Brave New World" by Aldous Huxley: reproduction and child-rearing needs to be outsourced to the government. It's the only way for the math to work. People just don't want to have 6 kids any more, and I don't think that's going to change. (And yes, people have to have 6 kids for population growth to work, because there's always going to be people who have 1 or none, so you need plenty of high-fertility couples to make up for them. People haven't stopped having kids these days, they've just stopped having so many.)