I think for now fiat currency is still very dominant in any field, whatever we want to buy, it is definitely fiat currency which is always the main choice, because there are still many countries that do not want to accept purchases in bitcoin, and are not ready to be paid with bitcoins,
Maybe if living in El Salvador we will get salary in bitcoin because bitcoin adoption is legal there, my country has not legalized bitcoin so I have to convert some of my salary in bitcoin for long term investment.