"What big idea of 2006 will be extinct in 2036?"
"We will be happier and richer if we reduce our birth rate" is the answer given by ecomonist Jennifer Roback Morse in Dodos, dinosaurs and declining birth rates.

On a hopeful note, the author "contends that small families are on the way out":

As the idea of over-population becomes obsolete, we will begin to re-examine many of the social attitudes and cultural changes that we have created around delayed child-bearing. We will begin to realise how odd and truly unnatural it is, that we expect young people to spend their years of peak fertility doing anything other than having babies. People create sexual relationships that are not based on the prospect of procreation, but are built on the understanding that pregnancy is something to avoid at all costs.

Following The Principle of Subsidiarity, which holds "that nothing should be done by a larger and more complex organization which can be done as well by a smaller and simpler organization," I hope that it is my children, not the State, who provide for me when I'm older.

[link via Catholic and Enjoying It!]