Bizarre coincidence that this program turned up on the tv schedules tonight. Still, it was a fascinating watch. But no, you cannot empty all the cities of the world onto non-existent farmland and expect them to survive. The Khmer Rouge tried that, and it didn't work out too well, did it?
I think we're well past the point of no return, but I believe God will intervene long before we make a complete hash of His creation. In that sense, I'm no pessimist.