> As one of the comments in the linked issue points out, dropping IE11 means they can also start using basic JS constructs, like Array.prototype.forEach.

Array.prototype.forEach is supported from IE9.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

EDIT: It is the nodelist api that isn't supported in IE. Not Array.prototype.forEach.

Quite a lot of these basic JS constructs even if they are missing (most aren't in IE11) are very easily polyfilled.

Personally I think it is fine that they drop support if they don't feel the need to support it. Bootstrap 4 isn't going to vanish.