So here's how things will work out if the banks get jack, and yes banks can be hacked. Anything on the internet can be hacked na why you're discouraged from making use of centralized exchanges or anything that makes use of a centralized server that can be breech.

But if our banks get hacked as the people you're talking about claims and they're able to pull it off, na just one click of the button and the funds will be recovered automatically because all the bank accounts that receive the money will be debted, another reason not to trust the banks. Crypto exchange are more suitable to be hacked because hackers know Bitcoin being stolen or other altcoins are almost not going to be recovered because they're operating in a  pseudonymous mode