Douthat tells us that the birthrate has fallen below the replacement rate. I haven't checked this one, but that sure sounds like good news to me. Has anyone noticed a shortage of people anywhere? Do you want more crowded parks and beaches, more traffic congestion, more pollution and global warming?
If people who want kids can't afford to have them or feel too insecure in their economic situation, that is bad news. But if we are seeing our population decline rather than rise (immigration will actually keep it rising), it's difficult to see the problem. As I say, it would be great news if this was really the biggest problem we faced.