Speaking of metadata, I hope “Apple Classical” develops schema specifically catering to classical music; the current schema works for pop music but poorly for classical music - songs and artists, really? Some useful fields would be:
Work - Genre; period; geography (country/region); catalogue number; edition/revision (inc. cadenzas); language (if any)
Tracks - Movement title/tempo; accompanying lyrics and English translations would be useful
Authority control would be essential (Rachmaninoff or Rachmaninov?) to finding anything useful, quickly. Some guides/talks would be great. Apple can probably take some cues from libraries (disclosure: I am a librarian) and programme created by orchestras.
Primephonic, which Apple acquired, enabled search at least by genre, period, composer, name, catalogue number, orchestra, conductor, artist, year, and label. Search results could be sorted on fields like recording date and popularity. I presume they will be building on that metadata and functionality.
They also included biographies similar to that found in programmes and liner notes. There were also discovery features, such as preselected playlists and ‘radio’. They did have courses - I think for an extra charge.