It appears that many banks are already using Ripple's XRP Ledger (XRPL).
Recognizing that it's not mandatory to use XRP to use the XRPL, but given how subpar keeping nostro accounts is, you'd assume that banks would be actively looking for a better alternative, including using XRP.
We keep hearing that the price of XRP has been suppressed for years. Following that logic, you'd think that banks would literally be hoarding XRP right now, no? If so, where's the tangible evidence that banks are not only using XRPL, but most importantly that they are buying XRP?
EDIT: Thanks everyone for respectfully sharing very insightful and enlightening information. Your contributions helped me fill a few important knowledge gaps!