Obviously BTC is a threat to big government and big banks, so they can't just sit idle and watch.
It's not threat to government, as long as merchants charge sales tax and speculators pay capital gains.
It's only a threat to banks if banks refuse to adapt. They could adopt it and create hosted wallets / accounts and Visa/MC/Amex could build a credit system on top of it, and they would make money faster than any of us here have. Historically, trying to oppose new technology has proven to be futile every time. Companies that adapt are the ones that make it.