My view is that banks cannot delegate the custody of Bitcoin to third parties, for in doing so they would cease to be banks... It may well be that they are genuinely struggling to grasp how Bitcoin functions (multisig, etc.), and, as you rightly point out, the risks of custody will remain their paramount concern. Engaging in this with shitcoins such as Tether is perhaps because, as banks, they are chiefly obliged to store shit.... Banks will also have to learn how to operate as exchanges, so they must start studying some internal architectures for handling swaps, transactions, etc....So they need coins...