People in developed countries are already having fewer children. Much of Europe--like Italy--is in decline. (I would think the refugees would be a godsend for those countries.)
I keep my fuel usage (I'm at about 1500 miles a year) in check partly by buying "all sorts of stuff on Amazon."
It's my position that conservation can be done on an individual basis without trading in stereotypes, and I don't believe we have to live like penitents to cut way back on waste.