I expect similar problems looking forward. Hard disks made today aren't rated for 30 years, NAND flash retention is much less than 30 years, and Blu-ray drives may be hard to find.
might not spin up. I recently booted a Sun 3/80 from 1990 and while the battery backed RAM that told it how to boot was long dead, the HD was not a problem at all. Once I replaced and re-coded the RAM, the machine booted right up. And this isn't just a one off story. I've got a bunch of machines from that era, and the HDs are not usually an issue (although occasionally they are).
About half of them still spun up and were readable. Probably could have gotten more with heroic measures.
Most 3.5 floppies were likewise readable.
Hard failures aside, I assume very slow charge decay might be somewhat mitigated by periodically copying files flash-to-same-flash (let alone another) -- or perhaps even rewriting them in place.
The best answer is "host a NAS that you actively maintain and has an offsite mirror".
I personally host an all-flash NAS for the performance and MTTF benefits over HDD. Since it's always on and performs regular scrubs there is no concern of bit-rot. The data I put there will be there as long as I'm around to take care of the box and pay the B2 bill.
That said - I'm at a loss to understand what software is ultimately worth using without modification after 30y....
I wrote a video game for my child’s birthday. Does that count?
For your child 100% so if that´s the goal why not?
Modification is a big word. Old cars can still be valueble in capital and make you feel much more alive then a brand new car.