Someone earlier mentioned how the Germans managed this problem, below is how the French handle care in old age.
Anyone with elderly parents or grandparents living in France can be subject to demands from French care homes to pay for their upkeep. It relates to the obligation alimentaire laws, under which people are responsible for their descendants or forebears if they are in need.
Just as parents are responsible for the care of their children, adult children are responsible for helping their parents and grandparents
Article 205 of the Code Civil says: “Children owe sustenance to their father and mother, or to other forebears who are in need.”
If these funds are not provided voluntarily then care homes may seek to require a child to pay. If they do not do so, a family affairs judge will be asked to rule on the issue, taking into account the extent of the parent’s need and the ability of the child to provide the funds.
If a parent has been irresponsible with money or failed to work through idleness, the court might not require children to pay, as their need must be “involuntary”.
It also must be said that French people cannot, without a lot of problems, disinherit their children. Moreover your inheritance is yours and does not get put into the marital pot.