So, what security problems come to your mind if we consider a duplicate token buried at 1 meter somewhere in the forest (and nobody really knows where it might be) ?
With PKI, I contact my spouse. Honey, can you revoke the key I'm carrying? It's been stolen. Thanks sweetie! See you tonight.
I'll admit the duplicate approach makes for a much better movie. The PKI solution is positively boring. Maybe we could throw in a spouse kidnapping to keep it interesting?
Your article makes a valid point about the catch 22 of U2F keys. I simply disagree with your conclusions that it is the user who should try harder to make U2F work. It seems like you are pointing out that U2F is fundamentally broken, but you haven't accepted that yet.