My personal view is that I would want to know. My future plans would change from planning for a future, to living it, and help ensuring those close to me with their understanding and are also prepared. I find within the animal world, we can take some parallels from them and generally they too know when the time has come and for example, go to a place that comforts them in preparation. Some too can use the time ahead of them to promote an understanding of their condition to raise awareness (and maybe even money) to further understanding and remedy so people benefit beyond passing over.