How about sending pieces of the password to different accounts in a decentralized way? You could do this for sections of the private key too and just remember the beginning part and end part of those sections. You'd just give those sections to anonymous participant anonymously so that nobody knows who they are and thus cannot blackmail them, they should have a certain amount of stake and then we all can guard private keys.
As a side note, bockproducers or witnesses could offer this but it might be a risk in making them a target because now they'd have something in custody.
So if you lost your key but knew the summary you could send a request for each holders' section to give you that whole section by providing them the beginning and end of each section.