Thanks for a great show, tries to tune in to most of them now days after you got #gridcoin on board :)
I liked the talk about POS systems and CC that you "load up" at home. Interesting ideas and thoughts. But it made me think on a company in the Nordic countries, called SEQR. It does a similar thing as you talk about, but not being blockchain off course. But what I wanted to point out is that the only thing they have done is software, and they are in the market on all the POS machines in all the stores.
They have one software on phones, that can scan a QR code or read a NFC tag. The cahier only tells his/her POS machine that they should verify to this other place instead of the bank. Then the software on your phone sends to the same system and they are both verified from both ends after the user verified by PIN code.
The idea is not very farfetched, and it may not be as difficult as it sounds. The difficult thing is to get the software on the POS machine.
SEQR can be found at https://www.seqr.com/