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Governments may not be able to completely shut down bitcoin but if governments like the US, Europe and other major powers impose strict bans and consider it a national security threat. That will be the end of bitcoin.
Bitcoin is decentralized and private in nature but what people seek and need from it is the returns it brings. So if it gets banned by the government or something happens that makes it unprofitable, people will abandon it and what's the point of it being immortal when no one needs it anymore?
Bitcoin is not a national security threat - it is just an alternative currency created in such a way that has all the advantages, instead of fiat. Bitcoin's decentralization makes it uncontrollable by anyone - so the government can't kill it and throw it into hell. Moreover I don't think governments will agree to boycott bitcoin when they realize that there are potential multiple benefits they can gain from it - so it's a win-win situation.
Of course it is possible to get the governments of some countries to ban bitcoin like a few years ago - but over time bitcoin has opened their eyes and then accepted it. Instead of banning bitcoin completely - the government will actually get high income for the country if it legalizes it.