Thinking about it this way also makes me realise how weird it feels to have different preferences for myself as opposed to other people. It feels obvious to me that I would prefer to have other humans not cease to exist in the ways you described. And yet for myself, because of the lack of a personal utility function when I'm unconscious, it seems like the answer could be different - if I cease to exist, others might care, but I won't (at the time!).

Maybe one way to think about it more realistically is not to focus on what my preferences will be then (since I won't exist), but on what my preferences are now, and somehow extend that into the future regardless of the existence of a personal utility function at that future time...

Thanks for the help!