Mondex needed special hardware for it's security properties. What we really need is https://en.m.wikipedia.org/wiki/DigiCash

Interesting read! Apparently its concepts were taken over by https://en.m.wikipedia.org/wiki/GNU_Taler but I've never seen that in use before so idk of it's the dreaded never to be done micropayments thing or not but hey, it's a start, and less dead than mondex.