Come across something interesting on fiat currency.   

The original article, as mentioned from "Clusterstock", argues about the slim possibility of Renminbi becoming the currency to replace the US Dollar.  Basically this won't going to happen as it is still under the heavily control of the Chinese government.

The author, Arthur Kroeber, pointed out one very interesting point on fait currency (emphasis ours),

The US dollar’s position as the dominant global reserve currency is secure. It boils down to this: in a fiat currency world (unlike the gold- and quasi-gold standards that prevailed until 1971), the dominant reserve currency nation must be a net debtor, not a net creditor.

This is because the principal reserve asset is the debt securities of the reserve nation. Other countries must have current-account surpluses that they can invest in those debt securities, so the reserve nation itself must run a current-account deficit. (The problem of recent years was not that the US ran a current-account deficit, but simply that the deficit grew too large – nearly 7 per cent of GDP rather than the sustainable 1 per cent of GDP or so.)