What could replace [the dollar]? The British pound, the Japanese yen and the Swiss franc remain minor reserve currencies, as those countries are not major powers. Gold is still a barbaric relic whose value rises only when inflation is high. The euro is hobbled by concerns about the long-term viability of the European Monetary Union. That leaves the renminbi.

China is a creditor country with large current account surpluses, a small budget deficit, much lower public debt as a share of G.D.P. than the United States, and solid growth. And it is already taking steps toward challenging the supremacy of the dollar. Beijing has called for a new international reserve currency in the form of the International Monetary Fund’s special drawing rights (a basket of dollars, euros, pounds and yen). China will soon want to see its own currency included in the basket, as well as the renminbi used as a means of payment in bilateral trade.

At the moment, though, the renminbi is far from ready to achieve reserve currency status. China would first have to ease restrictions on money entering and leaving the country, make its currency fully convertible for such transactions, continue its domestic financial reforms and make its bond markets more liquid. It would take a long time for the renminbi to become a reserve currency, but it could happen. China has already flexed its muscle by setting up currency swaps with several countries (including Argentina, Belarus and Indonesia) and by letting institutions in Hong Kong issue bonds denominated in renminbi, a first step toward creating a deep domestic and international market for its currency.

Roubini provides advice which the American economic policy-makers ignore at their peril:

This decline of the dollar might take more than a decade, but it could happen even sooner if we do not get our financial house in order. The United States must rein in spending and borrowing, and pursue growth that is not based on asset and credit bubbles...

Now that the dollar’s position is no longer so secure, we need to shift our priorities. This will entail investing in our crumbling infrastructure, alternative and renewable resources and productive human capital — rather than in unnecessary housing and toxic financial innovation. This will be the only way to slow down the decline of the dollar...