Social scientist Heather Schlegel is a futurologist. She recently funded (via Kickstarter) a TV series called "The Future of Money" which envisions future methods of payment that seem sci-fi.
Heather's view is that If the last three decades revolutionized the information and telecommunications industries, the next three may upend the basic tenets of finance: currency, credit and banks, as well as payment and transmission systems. Your children may even ask you, “What was it like to see that old-fashioned building called a bank?”
Imagine it’s 2040. You go to the grocery store, and when you look for the checkout counter there is none. There’s no place to pay for your groceries because you already did. When you walked into the store, a sensor identified you, perhaps from a ring or watch you were wearing that transmitted the information. Or perhaps you didn't need to wear anything special. Maybe a device in the store figured out who you were using a combination of facial recognition, 3-D body shape identification and your gait. Your unique identifier is attached to your digital wallet, which transmits payment for the groceries directly to the store.