I think the lower level feature that we need on any service holding bitcoin is the ability to provide an address into which the funds are automatically swept into after a designated period of inactivity. This address could be the address of loved ones, or it could be an address under your control.

Specifically, an address under your own control could be managed by some future tool that helps you manage a dead man's switch for all your crypto-assets. It would be silly to expect to implement a complex inheritance feature in every service that might manage small amounts of our bitcoin