those things are a cool idea but they definitely need a hard switch to enable them, at minimum, or people will figure out how to hax them remotely... i personally hate that fact about standard NFC payment cards
Discussion
they should have a pair small gold plated contacts that you have to touch to connect the circuit IMO
Ah! I saw that in a dream. Two rings - one on each hand. You tap them together to enable payments. I think my subconscious was working on this problem. I've been getting a lot of dreams lately, and its awesome.