That definitely is a big worry for crypto holders.
There is talk about a new ico called Safehaven.io which still is to be launched maybe this month. As far as I know they are planning to do what you are worried about. You can nominate the person whom you want your funds to go in case you die.
https://safehaven.io/

Here is an excerpt from their whitepaper that would interest you:
"Have you ever thought about how, at any second, something could happen to you? Have you ever thought about the day your family will face life without you? What about your cryptocurrency investments? What about those difficult markets with hundreds of private keys, exchanges and wallets? Will they ever be able to recover your investment without you? Can they trust anyone who would help them without the fear of something going wrong? Yes, they can! Safe Haven provides the solution! We are building a platform on the most popular and secure block chains so that you can stop worrying about your legacy!"