I think it is a good way to store a cryptocurrency in a card though it is more easy to carry and doesn't needed any internet connection to be used. In the other hand it is also very dangerous as it may be loss and has the potential to be destroyed and stolen by someone. I don't think it may work but it is really a good idea for me but more risky in some other way.
A good idea and realistic enough to be implemented, because in some countries there are already bitcoin ATMs, so the system only has to be integrated so that the security factors of bitcoin in the card cannot be used if the card is lost or stolen.