This is one of the few areas where I think there's a legitimately useful role for NFTs. WoTC (the owners of MtG) could "mint" a limited number of cards each year, just like today, controlling the rarity of certain ones, etc. People could pay WoTC for them, and they could be traded in the blockchain, which shows the "chain of custody" all the way back to WoTC, which is what makes it "authentic". Online tournaments could check your ownership of cards via the blockchain, and I can even see IRL tournaments checking the blockchain too, if you want to print a copy of your card.
They already do this sort of thing with MtG Online, I think you can purchase and trade cards in-game. They also let you send them physical cards, and they will give you the in-game card in your account in return. Not sure if they go the other way around.
From WoTC's perspective, one of the downsides of a "public" blockchain would be that they don't get a cut of any transaction beyond the first one.
They already do this sort of thing with MtG Online, I think you can purchase and trade cards in-game. They also let you send them physical cards, and they will give you the in-game card in your account in return. Not sure if they go the other way around.
From WoTC's perspective, one of the downsides of a "public" blockchain would be that they don't get a cut of any transaction beyond the first one.