If you're that concerned make a living will. My mother in law was obsessed with death with dignity yet when the time came she no longer had the wherewithal to do anything about it. I was just able to get the PoA forms sorted and that was it.
She was very tragic, by all accounts an abusive mother, but even she didn't deserve such a catalogue of misery towards the end.
Christmas Day 2003 husband dies. July 2004 only daughter dies. July 2005 only son dies. July 2007 surviving sister dies and so starts decline. By 2010 she was incapable of speech or understanding that chocolates were something you ate.