A will system that allows the transfer of someone's bank account to several people when they are permaed. As well as combos to lockers and things... just an idea. More ICish then the stuff disappearing.
Second, well, it's not a thing because you haven't made it one. You don't need code to make this a thing. It would just become a burden to the GMs. You just need to write a will and you need to pay someone to execute your will.
No need for code.
We also have marriage licenses which allow you to legally have someone who takes your shit when you die. Just saying. You want something that is basically a role play thing-- go role play and make that ish happen yo!