I think kids require more energy than the average 60-year-old has to spend. If the solution to that is then to just have the state look over the kids, then why bother messing with fertility? Just clone the children, or cook them up in vats and incubators. Enabling 60-year-olds to birth children seems like a pointless endeavor that will cause just as many problems as any other solution that's an apparent affront to nature/god/whatever.