So no, bags, no lethal injections. So were are so lucky here to have the choice in most cases, but if at the last minute, the illness progresses and the person cannot self administer- even if just by pulling on a scarf or other contraption- then it is normally too late.
And the next big step is the situation re Dementia or Alzheimers. As said above, the person has to decide very quickly and in the early stages- to die before it gets worse- as anyone asking for asistance has to be compus mentis on the day. Many argue that this is terrible unfair- as the person has to 'leave' when they could still have many weeks or months or some quality of life- and that to force a person to make the decision 'too' early is cruel. EXIT argues, and I agree- that one should be able to make a clear advance directive, with 5 criteria personally chosen- saying that, when those 5 criteria are clearly reached, the fatal potion should be given then.
I've been trying to make a list of my criteria, that is not easy. Perhaps something like
when I do not recognize any of my children or grand-children and think they are strangers
when I no longer show any pleasure at the sound of beautiful music, or bird song
when I begin to do really awful things with my excrements (sorry- but a very personal case makes me feel that way) like smearing them on my walls, my face and my bed
when I cannot speak or make myself understood
when I get distressed and violent due to the frustration of the above
That will do, I think.