As medical technology advances, these are questions that will have to be answered.
The big lesson here is: Make your wishes known, in writing, because you never know what can happen.
It is not out of the realm of possiblity to me that Terri indeed would NOT want to have her suffering dragged out as it has been. (I sure wouldn't) But we will never know, because there is no record.
Bones
Also, if you're thinking you might want to be starved to death, specify whether or not you want to allow food or water to be withheld by a consensus of surviving relatives, or whether you would wish to require that it be withheld. After all, it's one thing to say you would rather starve than sit unloved in an instution in a world where nobody cared whether you lived or died; it's quite another to say that you'd rather starve than be doted over by loving parents and kinfolk.