The problem with that is the purpose of a credit card system is convenience, especially the convenience involved in being able to represent the identifier in an easily compact manner. When it's a few groups of digits, I can print it onto a card or piece of paper, and just plug the digits in whenever I need to validate the number and run a transaction. You can't do that with a token. What happens when I want to use my friend's computer to pay for something on Amazon but I haven't saved my card number? Or when I get a new card? I get that the current credit card system is monolithic and outdated, but it's purpose isn't to be modern, it's to be reliable, convenient, and adaptable, and it does a swell job at those things. There's absolutely no need to spend astronomical amounts of money to replace this system with something more modern.