In my mind, the part that is most likely to fail is "return an HTML document that still contains the following text." Nowadays, more and more "HTML documents" do not contain any content at all, just some JavaScript that is responsible for then fetching and displaying the content.
> entering the characters http://www.longbets.org/601 into the address bar of a web browser or command line tool (like curl)
The part of this that's most likely to fail at some point is the "http://".
In my mind, the part that is most likely to fail is "return an HTML document that still contains the following text." Nowadays, more and more "HTML documents" do not contain any content at all, just some JavaScript that is responsible for then fetching and displaying the content.
The detailed terms of the bet include this:
> A 301 redirect from www.longbets.org/601 to a different URL containing that text would also fulfill those conditions.
I assume this would cover the HTTP->HTTPS redirect scenario.
It's all a matter of whether someone is willing to pay for the hosting.
Which is not, in my opinion, how things should be hosted on the Web.
Freenet had a different approach, even back in the early days (two decades ago). I interviewed Ian Clarke about it https://www.youtube.com/watch?v=JWrRqUkJpMQ
I wrote about it for years: https://community.intercoin.app/t/who-pays-for-storage-nfts-...
And recently I built Safecloud to be different: https://safebots.github.io/Safecloud/