Dying young: I have a huge stack of notes, so I've always planned to leave that to a trusted friend and give them permission to publish it in any form they see fit -- my ideal would honestly be to just have those notes published as-is, whether in a book or just viewable online, so you could see how things were going to go and what I wanted to say about these people who meant so much to me.
Runewriters doesn't look it, but it's a very personal story, and I wouldn't expect (or really want) anyone else to draw the remainder unless they really connected with it.
Alive but unable to draw: I'm not sure! I'd probably hold out for a long while to see if things would turn around or if I'd be able to draw again. I mean, I'm just coming off of a two-year hiatus, I wouldn't be beyond waiting a few years again. But once I've let go of the project and moved on to whatever came after my life as an artist -- I doubt I would still be invested the story.
I find that when my mindset changes a lot, I no longer have the same voice when I sit down to tell a story, and I've had several stories that I let go when I realised I didn't have the voice those stories needed anymore. If something that drastic happened to me.... I don't know if I could still tell that same story when the dust cleared. Honestly, it would probably end the same way it would if I died young -- when I was sure I couldn't draw it and wasn't going to finish it, I'd publish my notes in some form for the people who had been so invested all this time, thank them for coming along with me and apologise that I couldn't finish it with them.