Who doesn't use Telnet??? I still got my WinTin together with all the aliases from when I was MUD-ing!! What? It's insecure? Everything is sent in cleat-text? North Korean hackers can steal my coins and my Longsword?
Billions of people. It turned out that mobile apps are the dominant way for people to use the internet. Mobile apps have much better security, have a much better user interface, and are able to use native os features like taking photos.
Twas mobile apps that slayed the shell. ;)
SSH ate its lunch in shell contexts, and then those new fangled computer graphics and browsers pecked away at the crumbs.