Aren't both Visa and Mastercard US-based and thus subject to the same executive order? So chargebacks are probably also at the whim of the US.
That's kind of a two-way wammy.. If anyone owned money to VISA or Mastercard in Venezuela, the creditcard companies would not be able to collect those debts either?
I bet your bottom dollar they will be allowed to collect.
VISA and Mastercard don't (AFAIK) lend money themselves, unlike Amex for instance.
Chargebacks are initiated with the issuer's bank, which presumably would be in Venezuela.
Credit and debit cards are specifically exempt from sanctions. That said, the card organizations may use sanctions as an excuse to not go forward with the chargeback process (as in, we will gladly take your money, but refund none of it because sanctions).
Consumer fraud lawsuits, and they don't want Venezuelan cash on their balance sheets.