I think we should beware of losing sight of the overall problem, this is how a lot of industry that shouldn't exist gets to exist, prolonging the problem, when actually the problem has a quick fix.
The problem is we are destroying Earth for all our energy, steadily poisoning our environment whilst doing it.
There are variables we can play with, to cut down the rate of destruction, but with destruction still happening, it has to end with the same result, extinction.
Hence why I write a lot about how we need to go to solar.
I believe this will supersede the problem of farming and livestock mass effects, since solar brings with it technologies like "Solein", which will go a long way towards removing our food burden from farming.
Just my opinion, besides I have to confess I still love to eat meat, even though I hate myself for it, I can't imagine much life without it :)