Even at 70mph you'd still run into the problem pg expouses - looking like an effortless dork.
As for this bit - "imagine something that worked like the Segway, but that you rode with one foot in front of the other, like a skateboard. That wouldn't seem nearly as uncool." - have you seen the Scarpar? It's only 35mph, but definitely, definitely cool.
are you serious? this may be what the segway needs. Extreme segway sports. If i saw someone going 70 mph on a segway, my first thought would certainly not be 'what a square'.
... maybe. Looks a bit wobblier, but look at it in context - they are on a cycle path and they fit in perfectly well. Someone on a Segway would stand out quite a lot.
As for this bit - "imagine something that worked like the Segway, but that you rode with one foot in front of the other, like a skateboard. That wouldn't seem nearly as uncool." - have you seen the Scarpar? It's only 35mph, but definitely, definitely cool.
http://www.scarpar.com/video.html