Keeping archival copies is probably harder than everyone thinks.
- In 1980, I saved my files from college on a DECtape. Few of you probably even know what that is.
- In 1988, I saved files from grad school on an 1/2" reel tape.
- In 1995, I saved files on 1/4" cartridge tapes.
So, basically, "archives" I made 15-30 yrs ago are basically trash to me (I'm not even sure the bits would have survived on those that long, but that's another story.)
Note that even if I had a DECtape reader that I could interface to modern computers, what's the format? It was a directory-based, block-structured device where files tended to be non-contiguous. Also, to get the most out of it, we generally uses FPIP to compress the data. And FPIP used a dynamic compression technique. That means if a byte corrupted in the file, you could no longer decompress as that would change the frequency counts used to determine the decompression tables.
So, in the list of archiving problems we have: old media, loss of integrity of the media, the hardware format of bits on the media, the software format of bits on the media, and the software encoding of those bits. How long will it be before MP4, etc., are no longer used?