When my near-life feels completely pointless, and at the latest just before I cannot feed and/or clean myself, I intend to take steps to end my physical existence. Being heavily dependent on another is not unlikely to be a situation I would want to be in. Furthermore, caring for a helpless me is not something I wish to impose on my wife (she is eight years younger).
In my suicide I wish to minimise violence to my being. For options such as inert gas, pentobarbital or salts, I feel there is not as yet sufficient evidence for reliability around peacefulness. Graduated fasting appears to me, currently, to be the best option; reducing food and water before stopping them. This seems closer to release than termination, and on the evidence not too challenging. Furthermore, legal penalties for persons keeping me comfortable should be easy to prevent.
I believe I have received guidance that fasting should be my way to go. On two occasions a moth settled on my desk, sitting motionless for several days till death.