Ten years ago when I worked in an estate law practice, I remember putting together a will for a wealthy couple with a retarded adult son. They were doing everything possible to ensure that he was taken care of after their death ... trusts, with strict rules and multiple potential trustees ... letters filed detailing the environment they expected for him, including his favorite music and TV shows ... purchase of property for him to live, and money set aside for caregivers ... But they still couldn't be sure it would all work. They kept asking my boss, "Is there anything else we can do?"
And that was before these more recent cases of simply killing the disabled. We definitely all need to look at our legal documents very carefully, but we also need to be aware that all our preparations can be taken down by out-of-control courts (among other possibilities ...)
Scary, less for oneself perhaps than for disabled dependents, if any.