With a bit of research, you'll know that they already exist. Bitpay, Cryptopay, and Shift Bitcoin are just a few examples. I really don't think it's for me though, unless, an emergency takes place. This system would "possibly" require identification, a third party and all that junk. Kinda beats the purpose decentralization, ey? I'd rather keep my BTC and simply go with my regular debit card when purchasing stuff.