I’m also not entirely clear on what scenario I should be imagining for the “humanity had survived (or better)” case.
I think that one is supposed to be parsed as “If AI wipes out humanity and colonizes the universe itself, the future will go about as well as, or go better than, if humanity had survived” rather than “If AI wipes out humanity and colonizes the universe itself, the future will go about as well as if humanity had survived or done better than survival”.
I think that one is supposed to be parsed as “If AI wipes out humanity and colonizes the universe itself, the future will go about as well as, or go better than, if humanity had survived” rather than “If AI wipes out humanity and colonizes the universe itself, the future will go about as well as if humanity had survived or done better than survival”.