I think that some kind of regulatory body is still needed. In addition, there are many unique banking transactions which bitcoin cannot change. Therefore, I see the ideal - the adoption of bitcoin by banks and their joint successful work.
In my personal opinion, the central bank is still needed to regulate the financial sector because if it is not regulated it will be a source of economic chaos, observers and cyptocurrency users different from each other which results in the economy not being conducive. Of course the role of the central bank in regulating cryptocurrency is different from the application of fiat money.