Does anyone know what happens in the eventuality of Mark's death or incapacity? I don't think control like this is inherently wrong, as it seems to have worked

Does anyone know what happens in the eventuality of Mark's death or incapacity? I don't think control like this is inherently wrong, as it seems to have worked well for Google, but I do wonder what happens after the founders die. These rather extraordinary provisions for control of public companies make sense when being granted to specific, exceptional individuals, but less so as a general power that can be transferred. So, does anyone know what would happen in that case?