The European Parliaments Committee on Economic and Monetary Affairs (ECON) has come up with a report on cryptocurrency entitled Virtual currencies and central banks monetary policy: challenges ahead. The finding of reports shows that cryptocurrency will not replace fiat currency, even in the long term.
https://bit.ly/2NeLgLrSeemingly, this report just acknowledged the existing state of affairs - cryptocurrency is not able to replace fiat money just because of the tradition that established hundreds of years ago.
Crypto can be just an additional method of payment unless it is widespread among all the social groups (which could happen in at least 3-5 years).