If I were a gambler, I would take even money that England will not exist in the year 2000 (Quote from 1969). - Paul R. Ehrlich

Too many rich people in the world is a major threat to the human future, and cultural and genetic diversity are great human resources.

Interstellar transport for surplus people presents an musing perspective. Since the ships would take generations to reach most stars, the only people who could be transported would be those willing to exercise strict birth control. Population explosions on space ships would be disastrous. Thus we would have to export our responsible people, leaving the irresponsible at home on Earth to breed.

In fact, giving society cheap, abundant energy at this point would be the moral equivalent of giving an idiot child a machine gun. With cheap, abundant energy, the attempt clearly would be made to pave, develop, industrialize, and exploit every last bit of the planet—a trend that would inevitably lead to a collapse of the life-support systems upon which civilization depends.