With JavaScript now being updated each year (ES2015, ES2016, ES2017, etc.), how does Microsoft plan to keep IE 11 up to date?
They’re not going to. As of 2015, Internet Explorer 11 will no longer be receiving any new features or platform bug fixes. Only security updates will be provided to IE11 from here on out. Going forward, Microsoft Edge is the new browser and Windows 10 is the new platform.
See the FAQ for more details.
Will we be forced to support an increasingly “crufty” IE11? Will we be stuck with Internet Explorer 11 in enterprises till 2020 (the end of the Windows 7 lifecycle)?
If a significant portion of your userbase consists of Windows 7 and 8.1 users, then you’ll probably have to continue supporting IE11 if your users aren’t using other browsers.
Having said that, IE11 isn’t going to get any more “crufty” than it already is. It’s going to continue falling behind as technology marches on, but with IE, what you see is what you get. You can pretty much rely on platform bugs and missing features remaining as they are and develop workarounds for them as appropriate. The behavior of IE11 isn’t going to change in the foreseeable future, which also means that legacy sites that work with it today will continue to work provided they remain unchanged (e.g. won’t be updated with new technologies). So there’s a silver lining for you.