Of course they can, but every one of us have to find the best means to leave our crypto assets once we are gone. Didn't give this much thought until now but there is few options that immediately come to my mind:
1. Do it off the record. Just teach your chosen heir or several of them how to access your assets or were you have stashed your backup key.
2. Leave your private keys with family attorney or bank deposit safe and leave instructions for your heir to receive them after your demise.
3. There will be more and more services which can handle this like someone mentioned coinbase.
For now I am inclined to solution number one. I just have a private key with some simple instructions stashed in place I am quite sure some of my loved ones will need to check as soon as I am not here anymore. Damn this was depressing to write