I'm not sure this article is all that accurate.
"Segway" is a brand that has passed through several hands after Dean Kaman sold it a while back.
This sounds to me like the New Hampshire plant is no longer going to manufacture Segway units, rather than the technology being discontinued altogether.
Ninebot of China acquired Segway and uses the IP to defend their self-balancing inventions.
https://time.com/3822962/segway-ninebot-china/
It looks like ninebot still produces the Segway in China, and I don't imagine will stop soon.