It surprises me that you view the hard disks as a blessing and not a curse for the preservation of data. Sure they work if one is willing to actively propagate information forward. What happens when one stops? Within a few decades the archives die, and are not very likely to be recovered by the historians (especially if the recovery is happening centuries in the future).

Why may one stop being able to propagate the data forward? There can be plenty of reasons. The civilization as we know it may collapse (not die out, but collapse); we may run out of the (cheap) resources to produce more and more storage media; or more pragmatically the people who currently find the data valuable may die, which does not mean that the data will not be valuable to historians millenia later.

If we can ever hope to escape these dark ages, what we need is something that is able to withstand the test of time on its own. Unfortunately, I don't really know of anything besides paper and stone. Do you?