This reminds me of the book "Johnny got his Gun", by Dalton Trumbo. The book is about a soldier in WWI who get all of his limbs blown off, goes deaf, loses his sight, and loses his speech, from a bomb. In the story, the soldier becomes concious again and realizes that he is just a "piece of meat that keeps on living." Years pass, and eventually he is able to communicate with his nurse by morse code. She tells the military about him, and they communicate. He tells them what its like to be a vegtable, and he asks them to kill him. When he does not get his wish granted, he realizes life for him will be a living hell for the rest of his existance. I think when you're nothing but a brainless bag of skin, you have the right to die.
It is funny that the brainless bag of skin in your story was still able to communicate in morse code. Are you and your mother able to speak that way - or are you both among the brainless?
What you really mean is that when you are worthless to us you have a duty to die or rather accept us killing you. Terri is not simply dying, she is being killed.
Part of the issue with Terri Schiavo was what she wanted - your view ignores that and advances the notion of killing fields in our country.
Oh, and if the "brainless bag of skin" won't die in due time, then let's starve her. YEA-ARGH!
In pro-death fiction (The Shadow Box, Whose Life is it Anyway?, Million Dollar Baby) the imaginary people reinforce our healthy vanity, so we can nod our heads and say, "You see, they don't want to live like that".
In real life, as opposed to fiction, the sick want to live, not to die.