It also depends on HOW MUCH the population will decline. We're obviously not going to get to zero as long as people have sex. If the world population ends up s

It also depends on HOW MUCH the population will decline. We're obviously not going to get to zero as long as people have sex. If the world population ends up stabilizing around one billion, for example, or half a billion or whatever, we would be far from "doomed", only a lot more sustainable than we currently are. Absent a whole lot of global catastrophes, it might take a couple of centuries for us to get there. Meanwhile everybody cries bloody murder because they have no idea how to extrapolate current trends into the far future.