I like the idea, because it's going to take years before cryptocurrency will become mainstream. However I don't see this happening, because even the elder people are already getting used to online banking. So my guess is that the paper bills will just become history someday, because it's actually worthless material that's really costly to produce. It's supposed to represent real gold. Now you could argue that gold is also just a material, but at least it has some valuable characteristics, like conduction. That's why it's used in about every electronic device, like your smartphone. And since we love our smartphone so much and gold is a limited resource, gold actually represents real value. So if a cryptocurrency would represent gold, it would be the same thing as a dollar bill, only a lot cheaper to produce and transfer. Nevertheless I like your creativity! It's the kind of out-side-the-box thinking that we need to make cryptocurrency more accepted.