Alternatively, this could be achieved by an affirmative action on the grantor's side. For example, require a signed transaction from a particular wallet every X months, if no transaction occurs, then trigger the switch
My favorite version of this is having a list of beneficiary addresses that can request to have access to the funds; you can cancel the request at any time within some time period. No fancy token required. I built a demo of this a while back: https://github.com/smartcontracts/dead-x-wallet
Yeah, I think the problem with this is that you need some way to store data without anyone being able to read the data on the blockchain.
There must be a middle-ground between your solution (dead simple) and the OP, which I find to be overly complex with all the "Curse", "Archeologist", etc. shenanigans.