The physicality of published work means it can move past a sell-by, due to expire, out of date and out of time, defunct, archaic, old-fashioned, and historic. But this is acknowledged in the scheme of things, and items not first wanted by many will lie dormant, ready to be rediscovered and revalued when their sell-buy time comes.
When everything is always on both sides of the line that says it’s published, the threshold of rediscovery may have no meaning: impossible to see over the edge that’s not an edge; round the corner that’s flattened out; into the future that contains all of the past.
Future proof is needed for any future-proofing. No going back, so don’t look forward.