We need to consider some of the problems associated with a complex object - Bitcoin, to give a solution to the problem related to their fate after the death of the owner.
1. If at that time BTC is allowed to legally exist as an asset: you can use some inheritance services. I think there were quite a few such projects built on the blockchain at that time.
2. If BTC has not been officially recognized as an asset, try to proactively hand over the wallet code & password to the person you want to give. You can give it directly or through a representative, or lawyer, or many lawyers and each person holds 1 piece of necessary information. If you are a fan of the OnePiece anime, you can hide it on LaughTale Island

3. If you forget to give it to the next generation: all the BTC will be at peace and all other holders will receive a portion of the benefits from that. You receive silent thanks ^^