Plainly answered... Yes, crypto currencies can actually do away with fiat but you know, due to bad and corrupt government we have almost in all the major countries of the world today, it's gonna be difficult, we should all know that for crypto currencies to successfully do away with fiat, it has to become our major currency for buying and selling both offline and online, we have to be able to spend it in the real world for goods and services just like fiat is being spent, but I also figure that another problem we are actually going to have is those in the rural areas that don't have any means of connecting to the internet, even if given a smart phone, don't know how to operate it cus they are not learned, this is why am of the opinion that before crypto can take over from fiat, this generation will must have been wiped off from the face of the earth.