It is not happening, bitcoin cannot replace FIAT banking system. Government will not allow it. As it is at this moment bitcoin cannot replace the money in the transactions that we make day by day. Bitcoin has some disadvantages, it has high fees, a transaction cannot be reversed, it is diffficult to be obtained by many people, all wallets are anonymous. Some of these disadvantages can be advantages for some people, especially the anonymity and the non-reversal of transactions.