My father died recently and didn't leave a mess behind for others to clean up. He was caring and considerate of others for the entire 47 years that I knew him. He worked most of his life, supported his family, and was a jokester and a mensch. His death was a shock, and it came far too soon. The kindness and the caring he radiated will be sorely missed.
In the five or ten years preceding this event, he began to scale back the material assistance offered to his offspring, encouraging us to become self-sufficient. My mother is presently encouraging the same self-sufficiency. My parents were aware that they wouldn't be around forever and wanted to prepare their kids for their future. The neediness of her mentally ill offspring includes an emotional level. We might be taking care of ourselves to begin with, but despite this, losing a parent involves a certain amount of fear.
If you give a person a fish, they are fed one time. If you teach them how to catch their own fish, they are fed for a lifetime. You are not doing your mentally ill offspring a favor when you provide for all their needs and don't ask anything of them. When a person with mental illness reaches the point of being stabilized, more should eventually be asked of them. Parents owe it to their kids to help them learn how to survive. However, in the case of a disabled person, it must be done gently, cautiously and gradually. If a person with mental illness is to become self sufficient despite being disabled as well as vulnerable to psychiatric relapses, they must learn to manage their vulnerabilities while they are doing what is needed to survive.
When someone with mental illness is dependent on parents for too many of their needs, and then the parents pass away, the result could be institutionalization. To avoid this, the disabled offspring in a family must learn to rely on each other and on themselves. In nature, a baby bird is kicked out of the nest at some point, and they can either fly or they can't. In the case of human beings, never kicking them out of the nest might seem like helping them, but they may never develop the ability to live on their own.
These are all generalizations and I am not saying this is the only way possible to do things. If someone is not able to provide for their self, institutionalization might be the way to go. In such a case, finding the best one could be done in advance. Funding is limited in counties. However, many persons with mental illness can live with a fair degree of independence, and can benefit from having a case manager.
In short, preparing mentally ill offspring for the day when the parents become disabled themselves, or become deceased, should be done by the parent. This can be done by weaning the offspring from various types of assistance.
For more ideas on this subject, contact your local chapter of NAMI.