Regarding archive.org, it’s worth to note that you can submit an URL for archival through their site. Here:
http://web.archive.org/saveAnother thing to note is that in the past they would retroactively apply robots.txt, such that if a previously archived URL was matched by a disallow directive in a later crawl of robots.txt, the page would be removed from public view. Fortunately they began reconsidering this behavior in 2017 though, and started not applying later robots.txt for some domains. Not sure about the current status of that though. Here’s a a blog post they wrote about it, from 2017: http://blog.archive.org/2017/04/17/robots-txt-meant-for-sear...
Meanwhile, even Google does not interpret robots.txt the way they used to: https://developers.google.com/search/docs/advanced/robots/in...
So hopefully crawled robots.txt etc will not prevent public access to archived pages in the future the way that it used to.
The main problem, aside from original owner putting directives in robots.txt that would cause archive.org to remove a page from public view, was that if a domain expired and someone else picked up the domain and made a robots.txt, then that one would be retroactively applied as well. And even if the new owner did not intend to remove anything from public view on archive.org, they could do so unintentionally simply by having a strict robots.txt and not being aware of what this would mean to archive.org when they crawled the domain again.
Another question though is, how are ancestors 500 years into the future going to know to look at the Internet Archive for the pages that OP made? And how will they know what URLs to look for? Though this same thing applies for most of the other solutions as well anyhow.
