So, I don't take this lightly.
Euthanasia has always been the contiguous point of human life for me. I'm against Capital Punishment, and Abortion, for similar reasons (the value of human life). This, OTHOH, has always been tricky.
Who's interest are we really considering here? If someone wants to die, for whatever reason, who is society-at-large to decide for them whether or not they should live?
I would argue society wants that person to live for their own reasons, that have NOTHING to do with the well-being or benefit of the of the person considering euthanasia.
EX: Say there is an eventual treatment ... how long should she be force to live to find a treatment that would be considered equitable? If she wished she was dead for 30 years, but a breakthrough made changed this after 29 years, is that a desired outcome? Is that "better"?
Shouldn't the person subjugated to the consequence be the decider? If not, who?