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 .

I imagine that there would continue to be the equivalent of "rare breeds" farms if this ever took off.

I don't think you can be cruel to a species because a species doesn't feel anxiety and pain.

"Now isn't that cruelty" - was meant at the species going extinct. Just a pun. Not a literal comparison with slaughter.