As both of my parents are getting older now, my father has told me about a folder that's kept in a room in the house that has details about this and that, my mother likes to remind me about this bank account and that savings account — and they're not that old that I feel particularly worried about it. Both plans lack any real detail and don't cover the full picture of their wishes if they become unable to make decisions for themselves. That will be left to the will I guess. But there's potentially much more that my siblings and I will need to take care of when the time comes. Much of it is mundane, pin numbers, final bills, closing down services and subscriptions etc... other areas are more heartfelt, carrying out their wishes, getting access to their digital photos and dealing with social media accounts and know what to do in these scenarios. I'm sure there's many more things too.
So the idea would be to design a service that helps people to capture and build a picture of what's important to them and what will be important for the people that care for them.
This service would also be of benefit to people who are faced with passing on before their time. For example it might help you plan how you'd like friends to keep in touch with your kids or store messages that could be delivered to loved ones at later significant dates.