[neartheplain]

I think you are going to have to rely on another human being (or perhaps a group of trusted individuals) even in that case.

Not necessarily. Bank safe-deposit boxes are a secure place to keep secrets. To guard against rogue bank employees, encrypt the stored secrets and keep the key at home on a sticky note. If you ever hit your head and forget all your secrets, just present your ID to the bank teller, pull the secrets out of the vault, and decrypt them with the key on the sticky note.

[brigandish]

In that situation I can see myself forgeting where I'd put the sticky note, or what it meant.

[neartheplain]

That’s why you write the whole plan down on yet another sticky note!

[brigandish]

Haha, believe me, I can make this plan fail if I haven't had my morning tea or coffee, let alone serious head injury!