It is not known what the durability is for an optical disc format that does not exist. There is no optical disc format that stores the required amount of data.

It is not known what the durability is for an optical disc format that does not exist. There is no optical disc format that stores the required amount of data. LTO tapes do store the required amount of data and if you want them to last extremely long you should make new copies every 10 years or so. Just like you should for optical media. Sure, some discs might last 50 years. But some others won’t be readable after 15.