@simon @philippe @timbray you're both thinking of the Wayback Machine. That's not what I'm talking about.
You should read the docs I linked for Archive.org's free S3 clone. Stable, long-term URLs for original content.
I don't know how well it would work for setting up a statically-generated blog, but it would probably be worth the trouble, especially if it worked with a CNAME from your own domain. You could pre-pay the domain for 10-20 years and know that the site would stay up.