There are two way about it, it always necessary to have a go thought before conclusion. To you and I we meant think we don't need central bank because we are using bitcoin which is operating in a decentralized platform, what about the rest citizens that doesn't know how to use bitcoin or any crypto currency, what will happen to our fiat currencies as well.
To me I think there is for central bank if not for and you but for the common man who don't his to use bitcoin.