Technologies change everyday.
Web is fast changing.
From static HTML, Dynamic websites and to WebAssemblies.
It's hard to keep up and skillsets change every few years.
But I see developers using vi/emacs/make/gcc skills for decades.
🤔What are the evergreen skills you can invest in (or learning now)❓
** Update on 12/14/2018 **
Check out this great post by Alex Fawkes, in which he discusses the topic more in depth.