What's I know the currently major currency between fist currencies and cryptocurrencies is USD, so I want to ask can bitcoin become the major currency in the future to replace USD?.
bitcoin can only be a mojor crypto currency not a major currency , government will not allow that to happen since it will also affect the economy of that country who will accept and use bitcoin as payment. You need to understand that its hard to happen they will always find a way to compete with bitcoin/ its possible that the government will adopt blockchain but will not use and support bitcoin they will create thier own so government can also be benefit from it. They will create one with stable price .