Culture can be changed - we changed the attitude toward and prevalence of cigarette smoking in 2-3 generations, we could change other practices as well. Success doesn't need to mean 100% adoption - material changes in attitude toward meat consumption (luxury/celebration vs everyday) would make a material difference in the overall impact. And yes, some/many ranchers, butchers, etc would need to turn to some other industry for income. Solar farms should do pretty well on ranchland. Full disclosure - I'm NOT a vegetarian and love a nice steak. My doctor has recommended I incorporate more plant protein in my diet. But I'm not really trying to convince anyone that they should do the same. I'm mostly reacting to the opinion that it's impossible/silly. My 2 pack a day smoker dad thought the same thing back in the 1960s. By the time he was in his 70s, he was a firm non-smoker. Things can change.
Edit: I'm also not trying to equate eating meat with smoking - one is obviously more harmful to society than the other. I'm just thinking about the cultural change that happened. Culture is malleable. Laws aren't a great way to affect culture, but social pressure is really effective.
Edit: I'm also not trying to equate eating meat with smoking - one is obviously more harmful to society than the other. I'm just thinking about the cultural change that happened. Culture is malleable. Laws aren't a great way to affect culture, but social pressure is really effective.