I don't see any reason for governments to illegalize Bitcoin.
It doesn't break any laws.
"Bitcoin is just an alternative economy and ideally people should be able to exchange goods in alternative economy if they so choose."
So governments should leave Bitcoin alone.
They cannot ban it as still, no one can "qualify" Bitcoin, calling it assets, money, shares, and whatnot. What is curious about the USA is that the US authorities will not be able to ban Bitcoin since it is protected by the constitution. This cryptocurrency consists of a code that is essentially part of a Word, which means its restriction will be a violation of freedom of speech in States.