Bitcoins will be hard for them to stop without shutting down the entire internet. Should a government act against bitcoin, it would drive the price through the roof.
i doubt every governments will ever work together, so this scenario is very unlikely, you will always have at least one government that will not do anything against bitcoin, many have already embraced it, so why, suddenly, they should go against bitcoin without any reason? no-sense....
Worrying about the goverment shutting down the internet is indeed an absurd thing to worry about. Consider that the whole banking system works under regular internet as well. Credit cards, banks, stocks... it all depends on the internet. Without internet, they kill Bitcoin AND they kill themselves. No one wins.
The biggest reason why shutting down the internet would be an unprofitable venture for the government is that they wouldn't be able to keep a check on us. A country shuts down internet thinking that they are better by themselves and they don't want their useful information to reach into other worlds through internet. Look China, banning Youtube, Facebook, etc. There will always be an alternative, just like how bitcoin is to fiat
