Cryptocurrency is the future of all payment method due to the decentralized nature which grants financial freedom and power to the people. However, for it to replace cash or the Fiat, it will take years of awareness creation. Up to date, some people do not have access to internet whereas others do not know how to access it.
It takes time to learn cryptocurrency because cryptocurrency is based on technology that is quite complicated when done by parents and children. And cryptocurency cannot replace FIAT because FIAT is the legal state currency.