I love your example very simple and understandable I thought. No doubt something very similar will one day be created when there is enough users on the system such that Ethereum becomes a defacto standard for how we pay for things. Crazy to think of the type of market penetration Ethereum would need to have however before such a scenario exists. With smart phones as infrastructure its definitely possible. Its amazing how this technology would be so absolutely impossible 20 years ago and impractical 10 years ago because of the lack of infrastructure. More and more humanity is becoming dependent on technology such that an “outage” would have greater and more far reaching consequences. Ethereum “the last great publishing technology” being the capstone.