I'm not down with the whole chip implant thing idea. Don't want us humans turning into cyborgs.
If people start using a "human wallet", it'll probably be because of biometrics or something like that. I think there're already some trials for self-service stores where you can grab what you want and just go. They've got the whole store covered in cameras and use facial recognition for the checkout part, it's pretty wild.
I find it very impractical to scan people for payment. Imagine you are in a queue in supermarket and somehow the scanner fails to scan you as a wallet to pay. I imagine it won't be a nice experience.
Same thing goes down today if your card gets declined, no matter the reason.