Unless you take the time to write your own testament, to assign who gets a share of your crypto balances, they'll be lost if you tell me. Since nobody controls decentralized cryptocurrencies like Bitcoin, it's impossible to revert transactions, or recover keys in case of a loss since there's no middleman. That's bad in the sense that none of your family members would be able to get access to your coins if he/she doesn't have access to the private key.
As such, I think that there should be a feature where it could be possible to detect the death of a person and distribute the funds to the owners family members. Perhaps it's not possible with Bitcoin and other cryptocurrencies which are based on its codebase, but it could be possible with a smart contract. Therefore, you should take the necessary precautions to make your own testament indicating who gets access to your crypto funds and leave them on a safe place where he/she could find it.
As such, I think that there should be a feature where it could be possible to detect the death of a person and distribute the funds to the owners family members. Perhaps it's not possible with Bitcoin and other cryptocurrencies which are based on its codebase, but it could be possible with a smart contract. Therefore, you should take the necessary precautions to make your own testament indicating who gets access to your crypto funds and leave them on a safe place where he/she could find it.