There are some possibilities that bitcoin can replace fiat, in some countries especially European countries do believe that in the near future bitcoin will be used by all people. In fact a place in Europe use bitcoin as the sign of exchange on some material things they buy such as in grocery stores, food and drinks in some bars. And there are some experts who believes that there is a big chance that bitcoin can replace fiat it is because bitcoin is flexible I mean by flexible is that it has more advantages that fiat money such as Privacy protection, free to transfer and hold and freedom to transact and many more.