Opus is now in preview builds behind a flag. Please see https://blogs.windows.com/msedgedev/2016/04/18/webm-vp9-and-opus-support-in-microsoft-edge/Jay Tuckey commented
Please prioritize opus over vorbis. Opus will be used much more in the future, and people can transcode from vorbis to ogg to get support in IE.
WebM is in development – http://dev.modern.ie/platform/status/webmcontainer/Jay Tuckey commented
It is so good to see support for this being worked on! Is it too early to ask for a vague ETA? :)