Bitcoin has been around the borders of financial markets for less than a decade, but is slowly gaining importance as an alternative asset class.
Can the government of any major country step in and do the unlikely?
Yes the government of a country is free to do what they want. The government has the authority to do anything against Bitcoin, it could be bitcoin banned in a country and Bitcoin could be used legally because of a regulation that regulates Bitcoin. Some of the weaknesses that exist today are Bitcoin does not get the trust of a government. Governments are usually frightened because Bitcoin sometimes experiences negative price shocks, so this makes the basis for decisions to be made by a country's government.
the government is not frightened but about close minded for cryptocurrencies because they think it's not yet proven to be a convenient method of payment and by that they will never accept bitcoin
until atleast, it's proven to be convenient to be used, however control over currencies also important and bitcoin's nature is decentralized, really the opposite and it's what makes the adoption becoming harder.