I'm tempted to drop support for IE entirely, and possibly any browsers that don't support at least ECMAScript 262.
This isn't just about how a quarter of the codebase is polyfills for legacy IE, it's also about how most modern scripts don't support it either (things I'd never use like arrow functions crashing IE by their mere presence) and how many of the new approaches -- like for/of -- are so brutally efficient compared to legacy methods.
Whilst there's a lot of new junk I see no legitimate purpose for other than making JS harder to use and maintain -- promises, import/type="module", arrow functions, endless "callbacks for nothing", etc, etc -- there are a lot of genuine improvements that make it harder and hard to justify continuing support for IE.
Particularly when the way I write pages it would/should gracefully degrade for non-scripting anyways on anything important. (since client-side nothing important should be scripted in the first place)
I dunno... are we there yet? Is it time to kick ALL versions of IE to the curb?