Just remember:
You could easily be hit by a truck today: No time to tell anybody about your secret stash of Bitcoin stamped on a piece of metal buried in your garden. No time to tell anybody the password to your bip38-encrypted paper wallet.
Where it is nice, that your Bitcoin are safe from the government and banks, it would be really sad, should you suddenly die and the Bitcoin are just lost, instead of supporting your own children.
So, I am less interested in theoretical ways to solve that problem, but more if somebody here actually did something to solve it.
You could also consider it like this:
It's a non-issue. If the money is lost, the money is lost. It's not as big of a deal as you might imagine because
you can always add more decimal places to bitcoin. So basically losing bitcoin would just make existing bitcoin more valuable. Losing them is no one's loss really (except the guy who lost them)-- It's just everyone else's
gain (in the form of deflation due to the lost coins).
I don't think it needs a solution. If we couldn't add more decimal places then we might need to be concerned with preserving the money supply, but because we can add more decimal places, it's not that big of a deal. And if you want your family to have access to your bitcoins in the event of your death, then make a will with multisignature keys given to the right people.