I like the idea mentioned of a source code escrow, and it feels like that would be a great place for national governments to step in. It reminds me of how the British Library requires that any published book have a copy sent to them for archival. Why not have similar laws in place for source code? If for no other reason than pure archival.

I wouldn't mind at all if it was all just purely kept in a metaphorical locked vault, only to be opened after some special conditions regarding the support and lifespan of the software were met. Even if those terms were like, "only after the original copyright has expired", aka 70+ years, it would still be so much better for the state of preservation of source code over the current norms. We have games that have had their original source code lost in under a decade from their publication. (Kingdom Hearts 1) Any alternative is better than the current state of things.