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.
There are already a few governments which have acted against bitcoin, and how do you think has that helped bitcoin? It is thrown around in the media negatively, residents of a country are thereby even restricted to use it because it is banned in their country now. Also, bitcoins doesn't have such a strong backing by a lot of people that the whole internet will be fighting for them. I don't think the internet or the people care about bitcoin as much as you believe they do.