Neat idea but I don’t think it’s reasonable to expect every physical coin owner to maintain rightful control of the NFT. I think we’ll first need to achieve widespread NFT adoption. Still a lot of dinosaurs even on this forum who haven’t touched an NFT
I'm admittedly one of these dinosaurs. I resist the digitization of things for the sake of digitizing things. What especially doesn't make sense to me is attaching a modern digital token to an older physical collectible. Maybe there's more evidence in the chain of ownership, but this is just one more thing that people will lose track of, I think, due to the NFT being secondary to the physical item.
Not to mention, Cas coins for example have been around for a while, and are swapped between people all the time - if you were to mint a token for a coin now, how do you prove ownership of someone to assign the token to?
I personally wouldn't care if I was in possession of a physical item but the not the NFT. The physical item is the thing that I see as holding value.
There was a Bitbill auction a few months back where the owner (who had nothing to do will the guy / guys that made BitBills, he was just the owner of the BitBill), minted an NFT to accompany the sale:
https://bitcointalksearch.org/topic/m.57812232Since anyone could mint a token, and "minter" isn't even the artist / creator, it's tough to see what value, if any, something like that adds.