But on the other hand, there need to be protections here. Just because a company merges or gets bought, doesn't mean they should be able to end their guarantees.
What about if, to be legally allowed to license streaming content, companies were required by law to:
1) Specify a minimum duration available as part of the buy button and all other text using the term "buy" or "license"? E.g. "Buy for 5 years" or "License now (min. 10 years guaranteed)"
2) Require some kind of insurance/escrow/backup in advance, that guarantees that if they go out of business, all accounts and purchases will transfer to another service that will continue to honor them for the time period specified (or full purchase price is refunded)
In terms of a minimum time duration, there are even physical analogies here -- books can yellow and their bindings crack and glue fail, vinyl wears out, floppy disks become unreadable after a decade or two -- I've even had CDs experience some kind of green growth in humid climates rendering them unreadable. So we already have a kind of pre-existing expectation of media purchases only lasting so long, on average.