I think it's going to be incredibly challenging to avoid potentially catastrophic harm to the environment due to politics and incentive structures. As far as food goes, beef and pistachios stand out to me as particularly environmentally harmful/wasteful, due to methane from cows and enormous water requirements for nuts, and it's not clear that anyone can change incentive structures to sufficiently change peoples' habits regarding these foods. (though in the grand scheme of things my understanding is beef and pistachios pale in comparison to habits such as flying for climate change.) I usually see people who think about this topic discourage the idea of technological development as a magic bullet, but I'm biased in this direction (it's also fitting for people who read hacker news) -- advances like impossible foods are inspiring to me. They've created "fake meat" aimed at traditional meat-eaters, allowing people like me to keep our luxurious food preferences in a manner that's much more environmentally friendly. They've had an impressive amount of success so far, with deals with chains like Burger King. If they can convert a sizable fraction of meat-eaters, they will have made an enormous impact on climate change.

You're putting it mildly. The second scenario is a delusional fantasy, I don't understand how it can be mentioned seriously.

We may end up closer to the first scenario thanks to the prospects of the third one. I hope we do.