I don't think he wants to get rid of mastering, but to actually have all the tracks, so the user can> adjust the mix, however subtly or hard he wants to.
If would have a great benefit for karaoke and jamming use if you could completely take out a track.
It would also allow for dynamics to change automatically based on the playback equipment and user preferences. There would no longer be a need to hard limit the mix to the crappiest common platform - OEM car stereos.
But most of all, there would be more freedom in how the music should sound. Which is what recording engineers fear the most.
In my practice room, there's a sign on the wall:
God doesn't believe he's a recording engineer.