by 2022? in 6 years? Hardly so...
by 2030 - yes, very likelly.
by 2050 - VERY sure. Not even small doubt. FIAT will be found only in the history books by 2050
Even in 2050, bitcoin cant replace fiat. Bitcoin is a global cryptocurrency and cryptocurrency cant just replace fiat currency.
Each country has its different fiat currencies. Its necessary for the economy of the world. In 2050, perhaps paper money can replace digital money like paypal, pm, etc but it will be according to each nation. Whole globe cant have one single global currency.