I think a catastrophic failure of prosaic alignment/control, if it happens after AIs have a lot of power, but before they are either superintelligent or deep into an industrial explosion (that is, when AIs aren't yet overwhelmingly more powerful than humanity), is somewhat likely to kill a lot of people (maybe everyone). If instead only ambitious ASI-grade alignment fails, or if prosaic aligment fails after the industrial explosion gives AIs a decisive advantage, then it's much less likely that a lot of people die (that is less than everyone), and also extinction is significantly less likely compared to permanent disempowerment (because a smaller faction/aspect of the very powerful AIs will also have sufficient power to sustain the future of humanity on some crumbs of their resources, if such a faction/aspect exists). The chances of extinction in the overwhelming-advantage eventuality are determined by prosaic alignment of non-superintelligent AIs (in the case of industrial explosion, they are just the same AIs performing the takeover; in the case of ASI, they probably have a lot of influence over how it turns out).
I don't see prosaic alignment being sufficient to avert permanent disempowerment (to any meaningful degree), if there isn't a much longer ban/pause that lets humanity ensure a much closer alignment of AGIs that would guide the transition into superintelligence (making it possible it's done competently). The AGIs need more than just have human-like values, but to have the even less familiar property of keeping the future of humanity in control, as opposed to developing their own interests and letting them take over the future. For example, putting another nation of humans in that position of power (that AGIs with an industrial explosion would have; or the power of being in control of creating ASI while knowing what you are doing) likely doesn't save the rest of humanity from permanent disempowerment (the way small island nations can't realistically expect to ever become great global powers), so this is a very high bar for what kinds of notions of alignment can help.
I would like to see someone make the case for prosaic AI safety work being useful. From what I understand, the argument against looks something like “Current attempts at alignment are shallow, and only serve to paper over misaligned behaviors without addressing the underlying cause of that misalignment. This will not scale to super-intelligence, which will be competent enough to both hide its misalignment and undertake necessary actions to kill all life on Earth while doing so” (if there’s more to it please correct me). This argument seems to me to be whats happening, but it seems there’s still some disagreement about this. Does the other side have robust arguments that are more than just intuition?