While we have moved to a more multipolar currency system, with the euro gaining ground since 2000 in international trade and currency markets, and the renmimbi making headway as well, the central scenario is still that the US dollar continues to play the dominant role, and retain its exorbitant privilege as the global reserve currency.
When the financial crisis hit with full force, the dollar swap-lines of the Fed with e.g. the ECB were crucial in rapidly restoring confidence in the money markets and in the financial system. Looking ahead, the outlook for continued growth in emerging Asia in the 21 st century will probably promote the role of the renminbi.