[iLemming]

Coffeescript did not offer anything but different syntax. It hasn't improved the semantics of the language. Some people liked it and some didn't.

Elm, PureScript, and Clojurescript are fundamentally different languages. Javascript today has bloated, and it keeps growing. Experienced developers tend to dislike it. Newbie developers struggle with it. It is no longer "a small language with a low entry barrier". ECMAScript specification is already bigger than Java's.

PLs of today and the next couple of decades will be striving for optimizing for programmer's productivity, performance, or correctness of the program. Javascript today does not fit in any of these categories. So it is only natural - the trend of using alt-js langs will only grow.