How do I make my grandmother understand that it's her time to go?

I'm 29 years old and I can honestly say that I'm ready to enter into eternal rest. I'm not depressed, but I've done everything I've wanted to do and seen everything I've wanted to see. Also, the earth is getting overpopulated by the day, and if you ask me, the human population should've gone extinct a while ago. I've been able to think of a peaceful way to depart, and would go right now except for one problem; my maternal grandmother is still alive at 91.

People are always saying how there's nothing worse than a parent outliving their child, how it defies nature. But they're wrong. There is something worse than a parent outliving their child; a grandparent outliving their grandchild. That doesn't merely defy nature; it crushes nature. I'm fine with dying before my own parents, but I am NOT fine with dying before my remaining grandparent. That would leave a really ugly stain on my family. Therefore, I really can't go until my grandmother goes.

And the thing is, it's way past her time. She's lived way longer than most people do, even by female standards. And yet, she doesn't seem to be able to understand that. She's had more than enough time on this earth, and she wants more still. What do I have to do? She's not an atheist like I am, so would it help if I told her I'd be right behind her in death? I'm just worried that my parents will find out about my plan to depart and take drastic measures to stop me. What if, at the next family gathering, I read aloud public obituaries of people much younger than her who have died. Would that her guilt her enough into leaving?