I doubt even European regulators can get so pro-consumer but during roll-out V/M determined whether your card can be DCCed based on currency (e.g. for a while USD- and HKD-denominated cards can be DCCed but a THB-denominated card cannot).

So, if the merchant/acquirer frauds still happen and are found to outweigh advantages in consumer "choice", in extremis a regulator can order DCC be rolled back e.g. no DCC for EUR-denominated cards and fine Visa Europe EUR50M a day til they comply.