I imagine that, no matter how popular this gets, there will always be a market for real cows, pigs and chickens. It's just going to end up being a high end luxury market. A whole animal for roasting is something that will never be able to made in a lab. Also from what I understand this process produces fairly homogeneous meat, meaning you're probably going to need a real animal to make more interesting cuts, or 'bi-products' like heart, marrow and liver. Combine that with the fact that there will probably also always be a market for real leather (which will also become a high end luxury product) and I can see cows being reared for a long time after this process becomes wildly popular .