There are some credit cards that are not linked to any Banks, for example, American Express. In this case you have to link a bank account for automatic debiting of the monthly statement or pay the bill manually.

It would be nice to have an option to link a credit card account to one of the cash (checking) account for automatic debiting of the credit card balance from the cash account balance.

It would also be nice to have a "forecast" of the checking account balance after the payment of the credit card balance.