Your idea is really great, because if the STEEM earned on Steemit becomes easy to use for daily needs, its value to users can increase. A marketplace where people can sell their services and products, as well as payment via crypto payment card or QR code, can expand the use of Steem beyond the platform. However, for this it will be necessary to take care of security, appropriate fees and legal facilities in different countries. Hopefully in the future your suggestion will become a reality and the Steam community will get more opportunities to grow.