This assumptions that crypto will replace fiat currency is false. some people will prefer crypto while others will stick to the Fiat they have known all their lives
Fiat currency will not be erase/remove in easily from the currect system. It will stay for sure, but we expect more adoption and use of digital currency in the future. New generation and millenials will prefer virtual currency since they are the most tech savvy people.They started technology at an early age and they are use to it. Older generation prefer fiat currency but as thier population diminished, fiat use will slowly diminish too in my opinion.