Have the XBMC Foundation considered taking subscription donations via Patreon?
https://en.wikipedia.org/wiki/Patreon
Perhaps just setup to recieve donation via Patron specifically for Team Kodi to create and beta-test new legal content addons from Team Kodi?
If they money could go directly to the developers of legal content addons for the official Kodi addon repository it might help encurage the development of new addons?