The most important line of security to bitcoin is the same as the security behind bittorrent; there is no central server or company that can have guns pointed at them. Governments get everything they get through force. Bittorrent and bitcoin were uniquely designed to never be affected by force.
The weak point is of course where one trades bitcoins for fiat. Those exchanges aren't decentralized, so you can use force against them again, which is actually a threat to FIAT, not bitcoin, but it's certainly inconvenient to us for now.
The end goal will be for everyone to desire to keep bitcoins and never trade them for fiat... That'll take a while, so the intermediate goal is for an exchange or two itself to become decentralized; Which is really difficult to do because you can't trust people with your money when you don't know who they are.
...But as I said, it's in the works. At least a dozen different teams are working on doing exactly that, using mathematics & cryptography to replace the merchant somehow. It's a bit over my head too.
Whatever they come up with I'm sure uncle sam will make illegal but at the same time be completely undetectable.
Merchants and most transactions in general are already protected from this kind of thing by 3rd party services. Bitpay.com, who has over 10,000 bitcoin-accepting vendors, offers a wide array of protection from exactly this problem.
We're completely on the same page, they'll do something nasty to hinder bitcoin's growth, I'd bet my life on it. However, historically these companies always had exactly one weapon- Crony capitalism. (Using the guns of the state to do their dirtywork and maintain their monopolies.)You gotta bare in mind hostile governments aside, there are a lot of big players out there with a lot at stake commercially - Mastercard, Visa, AmEx, PayPal etc. Don't think they want to see Bitcoin succeed
If the state is helpless to fight a decentralized foe, what can they do now? Lower their rates and compete fairly? Lol... Win/win for all in that case.
The best anyone I've read thinks that they can do is pressure/bribe legislators to move faster against the exchanges.
Give it time; they'll learn... And the process will be easier by they time big players do.
But there are already 3 institutional funds with bitcoin in their portfolios already. Since bitcoin is technically an asset class, not just another precious metal or stock, I'd say 2014 is likely the year that most other investment funds will need exposure to this class too. It's pretty unavoidable at this point.
