At this time the people who say it is impossible, but I would say this is very possible. If the user is bitcoin continues to increase, then there is no reason to make the bitcoin main priority and replace the dollar.
I would say that it's impossible. Even the price of bitcoin increases, it is decentralized and the government isn't willing to adopt this type of payment system or as a currency because they will be hard time to manipulate it. And instead of manipulating it for their people, the whales are the ones that can manipulate the government.