Card's two modern examples of this are the U.S. and China. The Chinese have been swallowing their conquerers for millenia. And I have little doubt, that the U.S. would do the same if conquered. To some extent, it is because both are built on ideals. Interestingly, the U.S. is giving China its first real scare, as the later becomes more like us in order to compete with us economically. And, as a result, China is once again, after centuries of turning inward, looking outward, as it starts to assert itself internationally.
Many, esp. on the left, bemoan that we spend so much time looking inward, and ignore the rest of the world. But we do this knowing that our place in history is secure. I suspect that a thousand years from now, our Constitution and Declaration of Independence will still be setting much of the debate about how man governs himself. How many other countries in the world can say that right now? Few. Much of the rest of the world view themselves in comparison with us. I think that is a good indication that we are doing a lot of things right.