I don't think they will offer bitcoin deposits because the banks are centralized and they want to get control of what they are using and since the bitcoin is not stable then it is not a good option for them because they might loss some profit or money if they will accept or offer cryptocurrency deposits so i think, they will never offer bitcoin deposits.
but they will allow it though. as far as there are no interest concern. you can deposit bitcoin in bank in my country
but the thing is they will make it as a fiat currency because of its stability
if ever bitcoin will be stabilized(the price will not be highly volatile like the scenario at the moment) then they will allow it to deposit and let it sleep with an interest
in the future maybe. not right now but a decade or something . when all bitcoins are mined . things will change for sure, the concern of the banks why they are not allowing it is because of its volatility