If bitcoin replace dollar many early bitcoin adopters who have lots of bitcoin in store will dictate the world economy on their terms.Bitcoin supply is limited,those who have good amount of bitcoin in possession will manipulate the market and become a self proclaimed governments.I hope bitcoin never ever replace any fiat
You are not correct about Bitcoin. It has the potential to replace not only dollar but any currency as said by the CEO of Twitter and Square Jack Dorsey that Bitcoin is a future currency. Japan is also an example.
I don't think so because look bitcoin isn't yet fully accepted around the world and not all people have a tool in ordet to access it such a phone and pc. Maybe it could in the future or perhaps, it could become one of the new way to make transaction. Bitcoin was good at online transaction so I guess it will be the number 1 mode of payment online and dollar will be at physical store.