Another method can be applied...
Any hacker who’d compromised a card number could predict the card’s replacement as soon as it was reported stolen—and then, using the date of the previous card’s cancellation, figure out the replacement's expiration date too. “The day that card is cancelled, as soon it gets rejected, two seconds later I know what your new number and expiration date will be,” Samy Kamkar says. “If I were doing fraud, that would be pretty useful.” The trick could be applied again and again, stealing new card numbers as fast as American Express could generate them.