For now, it looks like we still need a bank because many of us cannot use bitcoin directly as a means of payment. We also need bitcoin as an investment tool and our own bank because by storing bitcoins, we don't have to pay various fees like we do when we deposit money in a bank.
Yes, we cannot deny that banks still have a big role in our life. In my country, we cannot pay for goods or services with Bitcoin or other crypto coins, it must be using money printed by banks. Bitcoin or any other crypto coins are illegal to use for payment purposes here, they are only used for digital assets. Considering this matter, banks' role is still irreplaceable. For now, Bitcoin is still good for investment, it is legal already here.