I'm wondering this because is such a real threat to bank system and we all know how banks and governments are tightly linked !
BTC could make people more autonomous, self-resilient, being their own bank. You can use it like cash, making your transaction almost untraceable (or untraceable using e.g. monero or dash or laundry systems) : this is governments worst nightmare, isn't it ?
They can't!
The thing is the worst thing they can do is shut down exchanges, ban ICOs, whatever. But to shut down or ban bitcoin itself is just impossible. Sure, they could say on paper that bitcoin is illegal but people will continue to use it. Just like when in some countries where their currencies are extremely unstable people turn to using the US dollar even though it is officially banned(e.g. Zimbabwe).
If governments banned bitcoin, people are going to continue to use it. As it is a distributed ledger, governments can't just shut it down.