The species won't go extinct either, we can still keep some around in their natural habitats and zoos, which are both much nicer conditions than most farms. Preferably we won't keep around the breeds that were created for farming, they just aren't healthy animals.
The next quandaries are what do farm owners, farm workers, slaughterhouses, tanners, textiles, feed companies, agriculture focused veterinarian services and products, etc, do now that they're no longer needed?
I'm sure we'd work something out in terms of retraining and government support for new businesses.
[until the aliens bring tomorrow the mass production lines of cheap lab meat] Because of naturally gradual process of lab meat quality increase and price decrease there will be no point in time when suddenly "we have 70B animals we're no longer consuming "
But that's literally in your scenario. If you don't have an answer, that's fine, because all of this is idealism. I just never see any conversation pertaining to what we do with all the animals.
It seems like it comes down to a substantial culling, as letting them loose would be disastrous for a few obvious reasons.
Second: That's kind of my perspective. Ideas are cheap and easy. Idealism paints the perfect outcome, without the really hard parts of making it happen, or the incredibly complicated network of systems that would be effected by trying to reach the target. These are huge problems; entrenchment is incentivized and reinforced on many levels. We often don't solve problems, we treat symptoms, because it's easier than doing what needs to be done to solve the problems.
One quote from the article regarding media sharing tips for farmers: Most people do not understand the complexity of raising pigs and getting pork from the farm to their table. That means, “[a] good rule of thumb is to speak to a level a third grader [eight to 10 years old] would understand to ensure that things are not taken out of context.
Also, some species have been altered through selective breeding so much they would have trouble survinging normally e.g. rapidly growing animals that would have difficulty supporting their own weight after the age they would normally be slaughtered.
There would hopefully be more land for wild cows, chickens, pigs etc. to thrive after too.
What do you do with the 70B animals we're no longer consuming?