Is there a reason everyone assumes our own music Libraries, Match, etc. are going away when iTunes does? My guess is that the new Music app will basically be what the Music tab on iTunes is currently: our library, Apple Music, the Store, Radio, etc. Is there a reason that wouldn't be the case?
I've noticed that folks like to fill in the blanks with what they think will happen (and it's always a worst case scenario) and then get upset over these imaginary things as if they had actually happened already. It happens on all forums I've been involved in.
I agree that it's doubtful the people's paid music is suddenly going to be inaccessible.