> Storage of data for 250 years (metal rusts, dvds melt/warp, paper is not data dense)
I would think: LTO tapes are like 20ish years if stored properly, so you'd only have to copy them 10-15 times over the course of 250 years although that cost/effort decreases over time with ever more modern standards.
Magnetic media is not optimal for long-term storage: its strength is mutability not durability. Something like Project Silica is much more promising.
Could you keep the drives working that long?
For 20ish years stored properly with a few spares, absolutely, why wouldn't they?