Why have poorer countries made up so much ground the past three decades? In a word, ideas. Indeed, whether we can trust them or not, the ideas of economists are, as Keynes said, more powerful than is commonly understood. The disastrous postwar experiment with communism in China and statism in much of the rest of the developing world, among other things, prevented them from growing anywhere near as much as they could. But starting in 1978 in China, they have ditched these ideological anchors for more market-oriented approaches that have let them catch up to where they should have been all along -- and fast. Now, that doesn't mean policy is perfect; just that it's much, much less imperfect than it used to be. That's all it takes to become a growth miracle. (And that's why Scott Sumner thinks North Korea could grow faster than any other country in history if it reforms).
A world where every country has industrialized is one that will look like the world before any country had industrialized. The center of economic gravity has and will continue to shift east.