I can only speak for myself on this: If I was diagnosed with a terminal disease with a long and painful period of dying I would simply mixed up a hot load of something good and end the problem.
Actually it think that is your choice. What i object to is the medical establishment, the judicial system, in fact society as a whole, being obliged to act as a co-conspirator and facilitator of a suicide. All wrapped up in a sentiment drenched conceit of a 'death with dignity'.. with the family (and the family pet) in attendance and a medical practitioner administering a lethal dose of poison.
That is corrosive to any life embracing society. Of course our modern zeitgeist is infused, obsessed, absorbed with death and futility. So this is a predictable development for a society that murders its own infants.. and lays plans to do away with the sick, infirm, incapacitated and expensive. Have no doubt that this is at the heart of the Euthenasia movement and that it will move relentlessly to remove 'useless eaters' and those without the ability to defend themselves.
So i say take your own life, if you reject that all human suffering lacks any kind of redeeming grace. A principle that has been the bedrock of a Christian life since the dawn of Western Civilization. Just don't draw me and everyone else into to it to as an apologist, aider and abettor. Because i still think it a gutless and graceless way out. And no amount of official sanction and affirmation will change that.