This is true currently. But again, there's no reason to assume this will continue forever.

> If we talk about civilization at this point in time then its the global civilization of earth we are talking about.

Nice idea, but I'm unconvinced. What does "the global civilization of earth" even mean? The world always seems more connected than the day before. Of course, in 1914 it seemed more connected than ever before. In 1939 too. Yet our global civilization split apart at the seams and we were thrown into two of the most devastating wars ever. And both hugely impacted the economies of the nations involved. The U.S. has been at war almost continuously for the last 25 years. With whom? The global civilization of Earth?

Even if you restrict your perspective to purely economic matters, to a "global economy," this seems dubious. If we truly have a global economy, it's one disproportionately controlled by a single nation -- a situation many nations are probably unsatisfied with, but currently unable to change.

So you've reached the conclusion that other nations are now content to sit back and let the U.S. run the global economy forever. Where's the evidence? Just because no other country has been able to challenge the U.S.'s dominance over the world economy in the past 50 years, doesn't mean they've accepted this as the natural state of affairs.