Banking institution are under the regulation of the central bank and central bank is created by the government, so why would a government allow bitcoin to be a reserve, it's risky asset and banks are usually insured by the government so it does not really make sense.
I understand that other private institution are doing that, but banks, I doubt they win.
They would create their own centralized digital coins but would not trust or allow bitcoin to be their reserved.
I am more embarrassed by the fact that a person wrote that btc can be safely used for fast transfers, only according to official data, just the visa and the mastercard process about 60,000 transfers per minute, and the bitcoin network is only 10, the eth, in turn, is about 20, well, the fastest is half a PolcaDOT with 4000 transfers and xrp with 1000, so I think btc cannot be used for transfers within the banking system
