Ultimately, US is a liberal country. If bitcoins cannot exist here, it will exist nowhere and that is not the case since the Chinese are in on it too. Cryptocurrencies are the future and America is not backwards enough to put a ban on it.
Bitcoin actually needs America to survive, believe it or not, if America Bans it all other countries will likely follow and the usage will drop, but USA will likely not ban Bitcoins and the guys pushing the ban lost and they are assholes too..