4 is very interesting too but for usability the bank may also want to control (or at the very least) store backups of the private keys they issue their customers.
I read the article completely. It seems that they won't store users private keys and will let them to be the only and the real owner of their fund.
From the translated version of the article shared by 1miau (done by google translator):
The customer manages his private key himself, we have no way of accessing his Bitcoin, and so we do not store it.
They even encourage people to use cold wallets.
If you decide to invest in Bitcoin, we will help you with the purchase of the necessary digital purse, the so-called wallet. We want to support the customer so that he can keep his Bitcoins himself. We also offer customers a so-called "cold wallet"