Local, pasture-raised meat is a big improvement over factory farming. However, there is no possible way to raise 9 billion animals sustainably. There is not enough land to raise so many animals on pasture without devastating deforestation and habitat destruction.
Additionally, even pasture-raised animals require more inputs than plant-based protein, and produce more outputs in the form of greenhouse gases. If we’re truly going to switch to a more sustainable food system, everyone needs to drastically reduce the amount of animal products they consume. Simply having everyone replace their daily intake of factory farmed meat with pasture-raised meat is not an option.
It's also important to keep in mind that many of the “humane” and “cage-free” labels are deceptive. 99% of meat in the U.S., including much of what's marked “humane” or “free-range” is really coming from factory farmed animals. As Jonathan Safran Foer says in Eating Animals:
“We shouldn’t kid ourselves about the number of ethical eating options available to most of us. There isn’t enough nonfactory chicken produced in America to feed the population of Staten Island and not enough nonfactory pork to serve New York City, let alone the country. Ethical meat is a promissory note, not a reality. Any ethical-meat advocate who is serious is going to be eating a lot of vegetarian fare.”
Finally, any animal products that are truly produced by small farms that raise their animals in the best possible conditions are going to be limited and expensive. Eating more plant-based protein, such as lentils, beans, and whole grains, is a more accessible, affordable option for most people who are concerned with the environmental and ethical impacts of their food choices.