Streaming made the back catalogue disappear
The promise of streaming was universal access. What arrived was rotating access, governed by licensing windows that nobody outside the negotiation can see.
Availability is not preservation
A title can be delisted globally overnight with no announcement and no archival copy in public hands. For work that only ever existed digitally, that is closer to deletion than to going out of print.
Who is left holding it
Libraries and physical media collectors have quietly become the archive of last resort, which is not a role anyone planned for them.