Yes, this seems like the definition of a service you don't want centralized. Each of us should just find someone (or a few people) we trust, and each do it our own way. Much safer and more robust.
The good news is that it's trivial to implement a dead man's switch on Ethereum, or even Bitcoin. Unfortunately smart contracts can't keep secrets, so you'll still need to trust a third party with a private key if you want to reveal a secret in the event of your disappearance.
