Matt Gemmell:

That’s the reality of digital data: sometimes it degrades, but usually the technological ecosystem moves on around it, leaving it isolated and inaccessible.

I have so many thoughts about this subject that I've typed and discarded more drafts on it than I can count.

Perhaps I can sum it up:

No matter what you do, there will come a time when your files are inaccessible. All of them. Digital will never be permanent.

See also: This piece at The Newsprint and the commentary on it at The Cramped.