The problem is that if Bitcoin takes off, banks will still treat it like regular currency. Once you make a deposit, the bank will add it to a pool, and withdrawals will come from that pool. Your account holdings will still be a decimal formatted number in a database somewhere.
Not with Bitcoin. Sure, they could use a pool, but that wouldn't do them any good.
The reason for the pool is called Fractional reserve banking, and that's impossible to do with Bitcoin.
So as long as the hub is secure, then the network should also be secure.
This destroys the protection from wiretapping that quantum crypto promised.