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?.
I do not think BTC will replace USDT either now or in the future. The crypto market in the future will be a very good alternative to FIAT currencies, but it will not replace the FIAT currency. It is very difficult to implement crypto in all the organizations where transactions are made, but it can be a good alternative and offers many advantages: fast transactions and very low trading fees.