Court proceedings that would be sealed for 100 years. Secret material, say military records, that need to be secure in the present, but are important historical

Court proceedings that would be sealed for 100 years. Secret material, say military records, that need to be secure in the present, but are important historically at some point. You could provide a declassification schedule this way. You could do a delayed form of historical whistleblowing or confession, so that it doesn't cause you problems today, but history can know what really happened. Perhaps providing the equivalent of a 'sealed envelope' to prove that something was known or happened on a given date, without having to be present or active to prove it. It's fun to think of a puzzle, but presuming it was truly delivering on the safety promise, I can see quite a few uses. The real schemes though depend on a lot of varying factors, so in cases where the secrecy was critical, you can see why people wouldn't use it.