Personally, if I am in a situation where I am NOT going to get better and have a certain quality of life, I would want to have the option to end things once I had my affairs in order. I would like to have family and friends there to send me off... have a nice party... say our good-byes... and then be visited by someone like Kevorkian to finish it. I could give family members and friends the things I wanted them to have, sell my house and give the kids their share of the proceeds, and donate the rest of my stuff to goodwill or whatever. I'd have my funeral arrangements paid for (cremation, ashes turned into diamonds for each of my kids, the remainder scattered somewhere special or launched into space). I came into the world with nothing, and leave the world with nothing.
I do not want to be hooked up to machines, prolonging my suffering, postponing the inevitable. Save the healthcare expenses for the people who actually have a chance to recover and live a full life. I will have had my turn at life, with no regrets about leaving it all behind.