Bitcoins can not replace Fiat.  I am totally agree with it.  Because bitcoin is only limited to Internet it has no real existence.  Without Internet bitcoin can not  be worked. Fiat can be used by everyone but for using bitcoins one should have a knowledge of Internet and should know the working of it.  Fiat money is mostly acceptable form everyone is aware about it.  Where bitcoin is still limited to some people. Bitcoin has transformed the economy and introduce new ways of transaction but still it needs a lot more effort to reach to the reach of people.