What would happen if the world suddenly went vegetarian?

Well, extrapolate from India. The article doesn't mention it at all.

https://en.wikipedia.org/wiki/Vegetarianism_by_country#India

The article also fails to distinguish between dairy livestock and meat livestock.

It also contradicts itself: "Around one-third of the world’s land is composed of arid and semi-arid rangeland that can only support animal agriculture" while earlier stating "we would dedicate at least 80% of that pastureland to the restoration of grasslands and forests"

It lumps chicken with cows and other rumiants - a whole world of difference, not that chickens are ethically well treated, but they do take a lot less space and the "because emissions" reasoning is also very different.

Also: “Going vegetarian globally could create a health crisis in the developing world, because where would the micronutrients come from?” Benton says. Well, Benton could ask the Indians.

Vegetarians are 'less healthy and have a lower quality of life than meat-eaters', scientists say http://timesofindia.indiatimes.com/home/science/Vegetarians-...