It is said that bitcoin will destroy the fiat system but i believe that if this happens the world will change completly because banks and a lot of things will go out of market.
It is quite impossible for bitcoin to destroy the fiat system completely because government policies and banks won't allow this to happen.
However, there will an increase in the amount of people using by 2022. Almost everyone then would have heard of bitcoin and will be involved in bitcoin related issues in one way or the other.