To quote my own mother, " Be it acident or illness, if they have to put me on life support indefinately to keep me alive, pull the plug or I'll come back and haunt you."
I think it's a matter settled amoung family, bit I have to agree with my mother, if the only way to be kept alive is bt life support machines and no chance of living wihtout them, it's really no way to live and best just to let nature take it's course. It's different if it's an emegency matter and the life support is only temperary in order to do repairs/segery to the body so it can function on it's own again once healed up.
Just my two cents.
It wouldn't surprise me though that if time and nature could be charged with murder for people dying, they would be.