It depends on the place and laws. Disabled people in general depend on external support. Some places give it by default, by law. In others, people are assigned to a family member to take care of them. In other cases, they have to be lucky for a volunteer to take cake of them, who may receive monetary support or not. Else… they just die by neglect… :(

Loving parents make plans with other people to make sure their disabled children are safe when they die.