That's not really voluntary euthanasia as I read the article. It's pulling the plug, which is something different.
The idea is sound enough though and could be adapted for voluntary use if needed, although there are still offences in many jurisdictions which would cause problems for those people needed to set it up.
It's an issue I have very strong feelings on. The right to a dignified death should be sacrosanct in law when a patient is terminally ill but can give their consent, either in person or via a living will.
Lead me not into temptation, I can find my own way there...