I think we do't need any central banks for the crypto currency and for the market regulations is 50 50 because if controlled then may be the price is stable and some people will prefer this and central banks are important because people trust it more.
Central banks are very necessary and influential on the financial sector. if without a central bank I think crypto would be difficult to disburse into a real currency that can be spent and the central bank also has many uses, so we really need a central bank.