All of those are excellent. There's also the ability to just leave it at a lawyer/notary (they already handle deposits, they might even have a secure box at a

All of those are excellent. There's also the ability to just leave it at a lawyer/notary (they already handle deposits, they might even have a secure box at a bank, so you can piggy-back on them for this). Directors/Founders of Random Co. should just make a few copies a few pieces of papers that contain the passphrase and store them at their own home and ask a few relatives to do the same for them. Depending on their recoverability/safety/accountability trade-off they can increase the number of copies, they can increase the separation between the parts (eg. keys and passprhases), and so on. The big-big-big advantage of the yubikey approach is that it's a HSM, and you can't accidentally copy the key and leave it somewhere.