Apple Music

Seems unlikely, at least in the short to medium term. Currently Sonos is the only hardware partner Apple is working with. 

I doubt this is on the cards in the near future, but it's easily added with an Airport Express and an optical cable.

Does Naim gear play nicely with the optical output of an AE? I haven't tried it - but in a past life I had an Arcam DAC that hated the AE digital signal. 

I've had an AE wired to a switch and connected to the streamer with a cheap optical cable for some time and it's always worked. Not the best sound quality, but quite adequate for compressed streams like Apple Music.