Ask your non-dev peers if they know what the command line is and if they have ever used it or seen especially when most people use the web on their smartphone.
Anyone who deals with any kind of machine with a console port.
CLIs are current technology, that receive active development alongside GUI for a large range of purposes.
Heck Windows currently ships with 3 implementations. Command Prompt, Powershell AND Terminal.
CLI is ALWAYS fallback when nothing else works (except when fetish of people on HN). even most devs use IDEs most of the time.
Theres a pretty decent list of incompatible features, but its shrinking (mostly due to those features being EOL'd not upgraded)