If you put the key in a bank safety deposit box...then maybe as long as the Executor of the Will isn't crooked or doesn't also have access to the wallet..... 
Lol then the executor will took all your coin 
,why not use some apps now that has this feature ?I believe that Infinitus token/ apps can help you manage your coin to be in time deposit and will be allotted to your successor in right time.
https://inftech.io/
Quote
Use. Own. Earn.
An Asset That Safeguards
Your Assets
their Motto ..
I am not affiliated to this company i have just read their site some time and got my interest .