If they do add that, they should specify VP8 and/or VP9 and/or Vorbis and/or Opus rather than just WebM.

The Opus audio codec, which was co-developed by Microsoft subsidiary Skype, would be useful both for WebRTC, and the alternative Microsoft favours, ObjectRTC.

VP8 and Opus both get mentioned in passing in the ObjectRTC spec that I found, but I don't know if they have the same status as in WebRTC (mandatory for Opus, optional for VP8)