didnt hear of any bank accepting Bitcoin yet.
That is not gonna happen because they have their own money, they only accept what is legal and regulated by the government.
Bitcoin as a currency cannot be regulated as banks cannot control, it will always stay decentralized and even if banks will create their own blockchain it will not beat bitcoin.
i don't think it even makes sense to have a bank keep your bitcoins, it;'s just like leaving your personal bank in the care of another bank and hoping it will be safe, why didn't you open an account with them then than setting up your own bank?
i think they will become a bridge between bitcoin and fait money because the basic need is the exchange to fiat for every customers all around the world. in some of the countries it was already declared as payment system but not a legal currency, it's a bridge for faster transaction but still it is subject to the
law of the government and there is no way it will be the same essence as legal currency and i think it would take away long for this.