A basic economic property of any currency is the ability to hold its value in the long term. While Bitcoin's ability to hold its value is evident, since there is no central authority to control the flow of BitCoins and the current traditional method of transfer of value from a deceased person to their legal heir's depend a lot on a central authority, how could inheritance work with bitcoins. This is not a open ended question asking for opinions but an attempt into finding if the protocol or any other system has been attempted in this direction. This could include both planned transfers and those that are not planned for.
nlocktime transactions are probably the closest thing you have at a protocol level.
Essentially, you can make a signed transaction that pays a bunch of your relatives on January 1st 2016. If you should die before then, the transaction goes through and they get their inheritance. If you are alive on December 31 2015, you would publish another transaction that invalidates the first transaction. If at this point, you want to continue with the same estate plan, you can publish another transaction for July 1st 2016 that pays out the inheritance. And again, on June 30th 2016, if you are alive you would publish another transaction that invalidates the TX about to be published on July 1st.
You can do this as long as you want and a similar transaction can be used in place of a trust (X gets some amount of bitcoins on their 21st birthday). You do have to be careful about this, as the bitcoins you're dispersing must not be moved in any way on the blockchain for the nlocktime transaction to work.