Right now, digital technologies are developing very quickly, and it’s quite possible that in the near future we’ll already be hearing about the ability to open cryptocurrency accounts in banks. More likely, however, banks will charge fees for this service. I doubt that banks will start offering deposits in bitcoin anytime soon, since it’s still too risky for them. And even if such an option appears, there’s a chance we won’t be able to access those funds as quickly as we’d like, for example, if we want to sell at a favorable rate.
Banks not accepting Bitcoin at this time is more of the stands of the central banks than it would be commercial banks. No one wants to second class their currency while making Bitcoin look as though it’s a superior currency even when it is.
Banks would someday find means to custody people’s seeds and coins for several purposes ranging from loans to trading with hopes of making profits from it. It’s a business established for the purpose of profit making.
My point of wonder would be, the individuals that would see having their Bitcoins with banks for a good or better safe keep.