M-Disc BD is doing the right thing by being readable by common consumer drives, though -- I'd be a lot more optimistic about finding or salvaging a BD drive to read some discs in 50-100 years, since even just the PS3 shipped in big enough volume that there will be some forgotten somewhere, than any specialty formats.

The NASA tapes problem (where they couldn't find drives) is definitely a concern on longer time scales. USB seems widespread enough, too.

It would be cute if someone made a self-contained archival device with display, designed for 100+ year lifespan. Solar powered (although generally external power is a simple enough interface that as long as specs are given, it shouldn't be too hard to recreate), multi-language, redundant, etc. Ideally with periodic integrity checks, a duplication function, etc. built in.

Seems kind of like an Internet Archive project, or OLPC or something.