Bitcoin its just a currency and a payment option doesnt have a country running with their currency,and big companies doesnt work with bitcoin value or price to import and export ,soo bitcoin wont replace nothing,it can be mainstream that will be just a way to spend and pay to another person or companie wont rule the world.
Now there is someone I can agree with. True bitcoin is a currency/commodity and I think it should stay like that. More people will be investing from it if it stay like this. Forcing it to become a fiat will make it fall.