As the artist formerly known as Puff Daddy rapped, it's all about the Benjamins. That's $100 bills, and there are more of them in circulation outside of the U.S. than inside, thanks to the primacy of the dollar as the world's reserve currency. But according to the man who wrote the book on the subject -- "Exorbitant Privilege: The Rise and Fall of the Dollar and the Future of the International Monetary System," published by Oxford University Press -- that's all about to change.

David Brancaccio sat down with UC Berkeley economist Barry Eichengreen and asked him to break down what that means for the average American.

And what will replace the dollar? Eichengreen has an idea. Actually three ideas.