So, I'm not an iTunes user, and I'm certainly not an Apple user in any way shape or form. However, I also don't buy individual songs or albums (haven't in years). Instead, I pay $9.99/month for Spotify Premium accounts for both my spouse and myself. I'm perfectly happy with this, and it allows me to listen to music in the car that is ad-free, with tons of choice and lots of introduction to new music.
HOWEVER, for my wife it's a different story. She teaches Yoga, and one important aspect of yoga is that it is often put to music. She spends a significant amount of time browsing the iTunes store looking for suitable music to put into her classes. When she finds one, she'll buy it, and add it to an existing playlist, or one that she's working on. She probably has about 100 playlists (if not more). Playlists are important, because the music she plays dictates the tempo of the class, alters your mood, etc. and she has different playlists for different styles of classes, and so things don't get too repetitious.
I would be worried that if she can no longer buy songs and organize them into a predictable playlist that can be played NOT on shuffle, it will significantly impact the way she plans and teaches her classes. She is a BIG user of iTunes, spending hundreds of dollars per year, and I don't know that streaming will necessarily work as an option for her.
What's more, the ONLY reason she's with Apple is because of iTunes. If it wasn't for her musical needs, I would have moved her to Android a LONG time ago. If Apple ends up ditching paid music downloads, then there probably won't be any reason for her to keep using Apple products.