I believe technology will help a lot. From poo-powered buses to using human hair as conductors, we will find out more and more ways to put human life in tune with our planet.

Of course, our planet is very limited, and we might reach a point where technology can't keep up or a point when it's too late. I doubt (or really don't want to believe) that this will happen though. As it can be seen in developed countries, as a higher quality of life comes, people tend to have fewer children.

The moral solution seems to be concentrating technological efforts in sustainability and heavily supporting the development of poor countries.