The first 60-80 years would be total hell.
The first thing that would happen is Africa, rural China+N. Korea, and a good part of the middle east would try to emigrate en masse to the U.S., Europe, and industrial Asia (Hong Kong, Japan, South Korea). Of course, this would totally destroy the economy of those regions. As soon as any area of the world showed a sign of significant economic deviation from the rest of the world, it would be swamped with immigrants, wiping out any economic differential.
OTOH, governments couldn't afford to treat their populace as badly as they do these days - as soon as they start, the populace would up and relocate en masse, depriving the governments of their power base, plus potential productivity/tax income. Businesses would see their labor pool shrink and costs rise - encouraging them to actually care for their workers.
Yeah, it would suck for those of us who have grown used to a more opulent lifestyle, but ultimately I believe that the way of life practiced in the U.S. is unsustainable over a long period of time - and for me, I'm referring to 1000+ years, NOT the next 50 or so.