Originally Posted by VGeorgie

That's not the way it works. Mastercard provides payment services between the merchant's bank and the customer's card issuing bank. As a merchant you use XYZ bank (or service, like Elavon), which then processes through Mastercard, who debits the charge from the cardholder's bank. If a merchant's account is stripped of being able to process Mastercard they cannot accept payments through it.

Even PayPal moves money through Mastercard and VISA, so they will definitely be affected. They will also be among the first to cut off a merchant's account if they're found to be engaged in piracy (and PP is known to just keep the funds).