> If you publish an ebook on your website and die and no one cares, the probability of anyone discovering it by happenstance 200 years later goes down to 0.

This seems overly pessimistic given the existence of archive.org (they accept donations!).

If archival institutions keep existing and improving their search and accessibility, it seems very possible that random websites will be accessible for a long time to come; 200 years is definitely within the realm of feasibility.