I would suggest that we shouldn't ever rely on digital archiving of important information. There should always be a copy of the information in analog, that can be dated & verified with analog methods.
This is one feature a blockchain excels at. People have stored the Bitcoin white paper in the blockchain. Anyone can then download it, and verify it is the untouched original.
You don’t really need the huge overhead of a block chain for that. You just need a hash and some redundant storage.
Block chain still handy to verify that no one tried to rewrite history and pretrnd hash was different in first place. And hashes on larger documents are never safe from collisions.
And to trust the guy who is storing the hash?
You could always put the hash on the blockchain. :)
Going fully digital with info, verifying with blockchain is all well and good, until a malicious actor forbids/prevents people from using blockchain somehow. if you've gone fully digital at that stage, you're in trouble
Only until the hash is broken.
Media only solves certain problems. Fundamentally, it’s also a custody issue. Storing archive material with multiple custodians is essential.