Inheritance can be complicated, so consult a professional about that, too. (Or at least give seed words to your inheritors or executors, so they can dominate any arguments.)
This is a good point. When XMR is one day worth $100, $500 or $1000 USD in the years to come. You gonna maybe want to let someone know how to access that juicy XMR wallet(s) just in case you die suddenly (car accident, heart attack etc).
Who to trust the keys to your wallet? I would prefer no one knows until I am actually dead.
Sorry, a bit off-topic I realised.That is what estate lawyers are for. You can leave the keys to the wallet(s) to someone that do not get to see them until you are actually dead. The legal firm must be trustworthy and, beleive it or not, most are.
You'll need to use cryptography. Combine public with private knowledge.
1. Store your private key in a keystore.
2. Protect your keystore with a long personal password and lay out a public description of it:
Something like: "My password is the name of my first 5 girlfriends, the one of my mom and my favorite actor and the date I did XYZ"
3. Give it to the people that know the answer.
Note that unless it contains some special characters you'd better do something pretty long.