They don't bother explaining that it is a CBDC (Central Bank Digital Currency) which is essentially just a ledger built on a blockchain but fully centralized. S

They don't bother explaining that it is a CBDC (Central Bank Digital Currency) which is essentially just a ledger built on a blockchain but fully centralized. So instead of using some independent bank's ledger which settles with other banks or gives out cash you have a single system with complete oversight. This is only useful if it eventually replaces the other options. My question is, if there are balance limits from the beginning causing overages to be "swept" out of the system and into a bank account, what happens when there's no longer an external bank account to sweep the funds into?