I was wondering about this too (in terms of adsense earnings). I was thinking that i should tell someone about my hubs and how to put in their own adsense ID so that they could earn the revenue from them.
I also had a look at the adsense faq and it says:
"Though our Terms and Conditions don't permit transfers of account ownership, we do allow you to update your payee name to fix misspellings or to make adjustments for changes such as marriage, death, or company mergers."
So I guess your heirs could change the adsense payee name to theirs so that they could cash the cheques.