There is nothing like having a central bank for cryptocurrency, thats not going to happen. Blockchain is open software and there is no one in control, everyone is in control of their money. If youve read Satoshis definition of cryptocurrency, he said that he wanted to create something that can help people send and receive money without the middleman, so cryptocurrency is like giving you complete freedom over your money and the risk is also on you. So there is no need for any bank.
I agree to that because crypto known as a decentralized which means no one can control to it. Also if Cryptocurrency have central bank then it will change a lot, the essence of being send and receive with out the third party or no middleman, also once we put our crypto in bank it will never be the same especially in transaction. So I think cryptocurrency will never be have a central bank and its impossible to happen.