It is an inevitabilitiy. Maybe cryptocurrencies will die, but fiat currency will FOR SURE die. There is no need for paper or metal money anymore. It is too convenient and there are too many advantages of digital money to not chose it over physical money. The beauty of crypto though is that it can be transferred across the world for no fee (except gas of course), and that it can be divided in as many parts as needed, so prices can be as precise as needed.