Switch or Integrate Squeezelite into Rune.
In this way all the music services will be available by default. It should be an easy add-on because even as-is anyone can stop MPD and install Squeezelite by themselves.
In fact why not just do away with MPD all together and go towards a more PiCorePlayer format....but on a Arch Linux core. People will be able to update Arch with no problem, updates to Squeezelite will be effortless too. Which means pretty much the "Working" parts of Rune will be maintenance free or greatly reduced maintenance.
In the end users will have a choice of either a music renderer via SL or a complete player with LMS + SL.
Rework the GUI to be a LMS Gui for the complete player and have only controls available for the SL renderer.
Best thing in you dev's can go back to your families and ignore Rune without worry of having a bunch of users wanting stuff. Arch, LMS and SL are all being taken care of and updates elsewhere...Rune just puts them all together in a pretty GUI and menu system.
When complete Rune can say it supports Spotify, Pandora, Tital and a ton of other music services as well as being able to work with RoonLabs etc. Just like that, the frontier for Rune can grow by leaps and bounds and long term maintenance can shrink to almost nothing.