I wouldn't equate possible changes in Oppenheimer to the Ministry of Truth in 1984, but books, movies, and music do get changed. (Han shot first). If you rely on streaming for all your media then you leave it to someone else to not only make the media available, but to give someone else the ability or responsibility for fidelity.
Some combination of libraries and personal collections are needed to not only to insure the availability in the future, but to insure they are unchanged in the future.
It's not a stretch to imagine the same people who want to ban or alter books being in the position of gatekeepers for some sort of streaming or online archive. You can fight the system to keep them from getting into mischief, but you will likely be more successful in keeping your own archives.