Remember the Segway?
Not sure what you're getting at here. Is it your contention that Kamen talked about it too soon, or too late?
I don't think it's the hype cycle that killed the Segway so much as the unwillingness of really any national government or major municipality to encourage people to whizz around on pavements using a powered device.
Nowadays, regrettably, that horse has bolted, and all sorts of sociopaths think foopaths are the right place for their badly-maintained future-electrical-fire on wheels!
What exactly did it revolutionize?