Will JavaScript ES5 be phased out? Will it be completely unusable?
Will ES5 be eliminated?
Will it be completely unusable?
Browsers are remarkably resilient to incorrect code. They’re far more forgiving than our development environments 
I say that because even if it was officially no longer supported in the web browser, it wouldn’t surprise me if it still just worked.
With respect to development tools, when I’ve looked I can see various frameworks across languages deprecating ECMAScript 5 support. To me that’s simply a response to what the current industry accepted standards are and the general agreement that ECMAScript 2015 (ES6) is more fully featured, than any impending danger that browsers are going to cease supporting ECMAScript 5.
I’ve not been able to spot any announcements from Google, or Mozilla, suggesting support will stop for their web browsers, but let me know if you have.
ECMAScript 5 still enjoys full browser support across the board:
https://caniuse.com/es5
…for now.
AI says that the underlying layer of “ES6” is “ES5”! For example, the “class” in “es6” is actually syntactic sugar, and the underlying layer requires “es5”
AI also said that “es6” cannot run alone and needs to depend on “es5”