This feels horrific, this initial event essentially is the end of his son as he knows him, and eventually he will actually die. My only vaguely similar experience of this kind of thing is my grandfather with Alzheimer's, but it felt like a natural end of life scenario (a horrible one). But with my kids, and I do believe in euthanasia, I wouldn't be able to do that either. I don't believe in god, but I'd always think there's a chance that maybe things will improve. Very tough situation.