Microsoft just made an announcement:
Brotli is included in Edge 15, which shipped today (11th April) with Windows 10 Creators Update.
I believe you need to be a member of the “Windows Insider program” to download “Windows 10 Creators Update”:
https://www.microsoft.com/en-gb/software-download/windows10
This will hopefully bring some of these benefits to Microsoft Edge users when it finally hits public release:
I remember the Brotli implementation in Discourse including some kind of “work around” for accept encoding / CDN handling so thought I would mention this here to allow both early testing and a little celebration
More info on Brotli on @sam’s blog