in my humble opinion btc will never replace fiat its just a coin that can be not copied or faked but speed of trades cant occur good and with general aceptancy if this coin never reaches atm good or a site like paypal to btc and bank in all in one and besides most of fiat rules the world and governements do acept it soo its fiat first then pay pal then others then btc into 4th or 5th forever i supouse
The main reason behind stopping people from using bitcoin is that they have never heard about bitcoins and that goes to developing countries and the third world countries, where they are totally dependent on banking system and are not ready to accept the change or innovative things
They are not ready to accept the change because of the lack of knowledge, they do not know well about bitcoin and do not have any knowledge about interesting features of bitcoin so they do not bother to adopt bitcoin and use it for their benefit, but for them the benefit is in their banking system, we have to promote bitcoin and have to spread its knowledge to every person.
Yeah we need to recommend bitcoin to people around us and show them the benefits attached with it and I am pretty sure that they will start using it.