The internet moves to fast for this kind of shutdown. Another currency will immediately take it's place. The US government should spend more time cleaning up it's own house and it's own currency. All this fuss proves only one thing - that alternate currencies are real threats to the USD and other traditional currencies.
If the USD was that strong, it wouldn't give bitcoin a second thought.
Their over-reaction is actually quite troubling.
Online currencies will only work if there is 1 established one