Call me crazy, but there must be a way to store data indefinitely, right? I mean, writing it on a piece of paper and putting that paper in a box can last practically forever, given its not actively physically destroyed.

Could we not come up with a tape storage that is write-once? Like a PROM, but in tape form? You do this, you add some checksums every now and then, and you just lock the thing away. How is that not going to last 100+ years if physically undisturbed?