The top of the food chain has been completely falsified by humans. We idealize it so much, to the extent that we routinely hunt, kill and trophy-ize the real top predators (who we’d have absolutely no shot against with no weapons) and imprison all of their prey, and artificially inseminate them, so that we can house them for generations for our consumption. We have created them, to the numbers we have. The world most likely wouldn’t change vegan overnight, although it would be the biggest dream of a vegan to have everything to change over night, but realistically it will be a slow decline– even if it’s not by choice.. it will be from the lack of resources to care for the animals, and their products will become more and more expensive (check out ‘cowspiracy’)
If we stopped killing animals, predators would most likely re-populate and keep the rest of the populations in check. The real overrunning problem, is humans, we are pretty much a virus at present moment with the rate we are destroying ecosystems. Perhaps some animal needs to start eating us?? If this argument was to be taken seriously that is.