How about future research and development. More effeciancy in production. Economics of scale. "Green" energey sources, once there profitable. Clean coal, nuclear. Nanotech, biotech, advances in chemical engineering, food production etc.
This arguement that the world is becoming overpopulated and theres not enough resources is an agruement put forth by progressieves to justify more "stateist" policys, comtrol, and taxes.
What crap, let market forces deceide. In regards to Chinda, India, Africa, etc... as their standard of living rises, their rate of natural increase will decrease. In about 50-100 years time women in these areas will average 2.1- 2.3 children per woman.