[smsm42]

They should be, but that assumes docs about what PDF format is survive, and they'd know how to read media on which PDF is stored (which is much more scarcely documented - do you know how your HD encodes data on physical level?) and have compatible hardware or know how to build one. That's a lot of hops and failure on any of them may render the whole chain unworkable.

And, of course, magnetic media can degrade and be physically destroyed as well as dead tree media. There are standards for long-term storage, but most of the info is not stored that way. We find most routine documents from thousand years ago written on paper, cloth, leather, bark, papyrus, etc. but today's routine information would never survive even a century, only specially preserved data - a tiny minority of it - would.