The reason the Segways have not sold well in my opinion is the price/usefulness factor. As awesome as these things are, they are MUCH more expensive than a bicycle which offers similar transportation capability. While they are cheaper than a car, they still do not offer the usefulness that a car has. They are somewhere in the middle, and the market just doesn't need that middling product. Because of this, it does not matter how amazing it may be to use, or how revolutionary the technology to make it is.
This is a similar issue, but it MIGHT sell to a certain market for the versitility of the terrain it can ride on...
Who knows...we'll see. Or not.