In https://github.com/yt-project/yt/pull/2896 I issued a rewrite for the interactive volume rendering.  There's been some discussion, but basically the path is diverging:

 * Merge in, and review via yt methods

 * Split into separate package (likely following a null merge, so that the history is preserved *somewhere*) and removing the existing interactive volume rendering

If folks have time, chiming in on it over there would be very helpful.  Thanks!

-Matt