High level question about virtual cards and the implication of their implementation: 16 digits doesn't seem like a very high number of available cards, especially since at least two of those numbers are reserved (checksum and IIN number). At some point numbers are going to be recycled, right? Or am I massively underestimating the # of credit cards out in the world? It seems like if a large # of people get a new # for every transaction that it would use up the available namespace pretty quickly.