I agree that the market for cheap used CDs is ending, not because of my huge CD collection one day being taken to a charity shop, but because I have watched ALL of the local used CD stores close, which were at one time on every other block in my town (and the towns I visited when traveling). Today, the only used CD stores are charity shops, and while I happen to live in a community with a government funded non-profit bookstore (Half-Priced Books) selling used CDs and LPs, their CD selection gets significantly smaller every time I visit.
What I think everyone misses on this topic is that everyone who prefers listening to digital audio because of its relatively consistent high fidelity and longevity, don't care so much about the medium, but how they access their music. Streaming can easily replace CDs, and then some, because it is cheaper per minute spent listening, the catalogs tend to be massively huge (far larger than any of us could possibly afford to purchase on CD), and in some cases offered in higher resolution or updated to remixes and remastered versions without any additional purchases. Why buy a new CD if I can simply look it up on Apple Music or Amazon Music and listen to it on every device I own, from my reference grade 2-channel system to my smartphone to my Amazon Echo Dot?
The mere fact LPs are outselling CDs in and of itself means nothing. A better consumer research study, to me, would be how many hours of listening per year is performed via digital vs. LP vs. Reel-to-Reel, per capita. That would be telling as to what preferences are leading the hobby.
