As far as I can see, the most robust fallback has to be some kind of distributed data store that can mirror humanity's vital information on the widest possible array of computer/storage systems, and which would literally take an apocalypse to wipe out. Depending on one brave person to fight what should be our common battles (and we do that everywhere, the heroes are always lonely at the top while their actions benefit all of us) is disappointing.
Data has to be duplicated massively or it is always extremely vulnerable. DNA figured this out billions of years ago.