in the future, will there really be a need for fiat currency? Government can collect taxes in crypto, determine how to allocate it, and spend it in crypto. Ppl can receive salaries and do all commerce using crypto. Loans can be done in crypto. Fundraising can be in crypto. Sure, problems have to be worked out in terms of scalability, does it have to be completely decentralized, etc, the value has to become more stable. But theoretically, is there any reason to have fiat in the future?
It has been established that governments can now do taxation without representation by printing more money (which is a tax on everyone holding the currency), instead of trying to get a bill passed that allows it to increase the tax rate. With crypto this would be no more. All increased taxation would have to pass a vote.
From an economic standpoint, the idea that a country can stimulate its economy by adjusting interest rates is tenuous. There is just as strong an argument that lowering interest rates has caused speculation and bubbles, with calamitous results. In a crypto market economy, capital will flow from where it is needed less to where it is needed more.
Of course they do, you cannot replace fiat because still there's a lot of folks who prefer to use fiat over crypto because in some reasons cypto is complicated for them especiall native people. Besides, folks are more used to it since they've using it for a long time since they were born up to now so. Moreover, there are some things that you can do in fiat but not applicable to crypto. Therefore, fiat cannot be replace but crypto could be still be used by everyone as another mode of payment.