Thanks! My comment is basically a tl;dr of a book I read called "The Coming Population Crash and Our Planet's Surprising Future" (http://www.amazon.com/The-Coming-Population-Crash-Surprising...).

Terrible title for a great book that isn't nearly as alarmist as it sounds. If anything it covers how we're not breeding to replacement numbers and are facing labour shortages as our current population ages in the developed world.

And maybe once you're done with that, you can read a rebuttal of sorts:

http://www.amazon.com/Coming-Population-Crash-Planets-Surpri...