@pools Wow. I wondered why my kpop list seemed extra short/kept repeating the same songs. Spotify does that sometimes. Just checked and a good third of my over 300 songs are gone. Thankfully my favorites are mostly older bands and those are with a different label. I see four bands I love that have disappeared plus many other songs from different artists I had found in one of my recent new music searches.
While those of us who listen to kpop might be less obvious, we definitely stick with spotify for kpop since they do (did) have so many of our favorites. Amazon music didn't have a lot. Grooveshark had masses. Youtube has most. Personally I will wait it out to see if they regain access. If they don't I will probably switch back to youtube music for my commute.
As far as demographics go, we are a wide range of ages/demographics. I (46 yr old woman) have friends into kpop from 12 yrs old or so to 65 or so, and that is people I have met locally thanks to conventions. Most of us use spotify.
Would all of us leave? Not immediately, but we would definitely keep our eyes open for a better way to access our music. I personally have used many music services over the years and will continue to move to better services as they become available. I left spotify when I got into kpop and couldn't find any good music and came back when they added more kpop to their service.