That is a possible course of action but it  may be not applicable for everyone. Not everyone has a person he can unconditionally trust.

But you may first divide the secret into two or three parts (no single part is enough to get to bitcoins), engrave them on pieces of steel or copper (too make them more longlasting), and have them deposited in places accessible by a few (not one!)  trusted people after you die. In this scenario you minimize the chances that you will be cheated by any single (trusted) person.

To be protected agains theft or burglary, make a backup of those metal pieces and have them hidden in some other locations.

I know it may sound paranoid and hard to execute, but it really would protect you and your heirs against any reasonably possible events.