Russia did it after 2014, not after 2022. So yes, it was seamless

That's not how it worked, Russia prepared well in advance before the war (admittedly, after Crimea-related sanctions scared the hell out of them in 2014). When the 2022 sanctions dropped, transactions within Russian borders kept working seamlessly because the banks were already using the Mir network for those regardless of card types, i.e. you can still use your Russian-bank-issued Visa today for internal purchases. And I firmly believe that Europe needs the same kind of security for its digital payment systems, something akin to IBAN that solved this for EU-wide bank transfers (which is why I'm not sure if it's wise to use some random commercial product as a base).

Of course, right now nothing can dethrone Visa/MC for international payments, besides perhaps crypto in very limited and often shady scenarios. And Europe can't really do anything about that. But that's a different problem altogether (one that annoys me to no end as a frequent purchaser of digital products from Japan).