I doubt the payment systems would run on a 3rd party cloud provider. But there are many other systems used by a bank, to calculate their risks, run their accoun

I doubt the payment systems would run on a 3rd party cloud provider. But there are many other systems used by a bank, to calculate their risks, run their accounting, do their regulatory reporting, all the network drives that are used across the bank, emails, that could be killed in such a scenario. That alone is enough to threaten the stability of the banking system.