Was anyone paying attention when the Dean Kamen wheelchair stopped being made? Was it cost/demand, didn't work? The wikipedia article says something about the FDA reclassifying it but that doesn't seem to explain why it stopped being made.
IIRC once the FDA reclassified it it was no longer classified as a "wheelchair" so it wasn't covered by insurance / HMO's which with it's cost pretty much meant it would not be bought by anyone.
https://en.wikipedia.org/wiki/IBOT