Web standard in progress for music notation!
http://createdigitalmusic.com/2015/07/next-web-standard-music-notation/ — please folks from this community need to get involved in this ASAP. We can't let the process be governed by only proprietary software makers and proprietary publishers. Musescore and LilyPond should have central roles here.
Overall, looks promising to move MusicXML to a neutral web standard or something.