A future feature I would love to see:
Ability to permanently re-order track play within playlist.
We can currently change the track order within playlists (e.g. based on Play Count, Last played, etc.) which is extremely helpful. Unfortunately this re-ordering is lost as soon as we exit the playlist.
Re-ordering tracks within a playlist according play count would help a lot with discovering music we have not played in a long while. I know this is partly possible via Discover or Focus but these do not currently allow access to playlists.
Basically, the equivalent to smart playlists (as in iTunes) would be a fantastic feature on top of the Focus and Discover.