Just stick a copy of your private key in a bank safe deposit box? That box will be inherited by your next of kin. Of course at this point you are (sort of) tru

Just stick a copy of your private key in a bank safe deposit box? That box will be inherited by your next of kin. Of course at this point you are (sort of) trusting a bank with your money (so why are you using crypto, again?) but it's probably safe and the safe deposit box + its contents would pass through all the usual legal procedures around an estate and more than likely pass safely to the intended beneficiary.