The following article is very interesting, it does not mention bitcoin but points towards a "cashless economy" where other payment methods will take over. Its like US is looking for a solution to the problem we have, its seems only a matter of time before they realize that bitcoin and other crypto-currencies may provide at least a partial solution

In summary, technology debit cards, online bill paying, gift cards, etc is quickly making physical currency a niche product rather than a mainstay of the domestic American economy. The most profitable Niche from an issuers perspective is the high-denomination $100 bill, and this fits neatly with the needs of many people who want a reliable and physically compact currency especially offshore. For everyday transactions, the Cashless economy is clearly on its way
http://www.zerohedge.com/news/2013-10-09/rise-c-note-and-cashless-economyEdit: he does mention bitcoin
Then there are the more obvious sources of demand: criminal enterprise and tax evasion. Google the term Drug bust and you wont likely see bitcoin thumb drives or euros stacked up next to the illegal substances. It will be stacks of $100 bills. And our Russian airport stash notwithstanding, the dollar certainly has an edge in money laundering and Wealth preservation strategies. Add to this the low rates of inflation in the U.S relative to many other countries, and you have a convenient (if bulky) store of value.