You're right! Only it is not clear when this will happen ... maybe in a year, or maybe in 100 years. But the fact that cryptocurrency will replace the current money is a fact.
I think that this should happen literally within the next 10 years. First, cryptocurrencies are being introduced into some gaming services, such as GoldenFever, and then they will start accepting it in online stores and various online services.
Many large and small online and offline stores and services accept cryptocurrency now.