Umm, and the meat we are eating today is not sustainable exactly WHY?
Has anyone besides me ever been in a real airplane? You know, you go to the airport, you go through security, you sit in a REAL AIRPLANE with a REAL PILOT and you go down the runway really, really fast and you fly?
And has anyone ever looked out that little window? Tell me, did you see cityscapes from horizon to horizon? No? Golly, wonder what could be done with all that ground beneath you? Maybe some of that land could be "farmed"? Perhaps some of that land could raise "cattle", "pigs" and "chickens"? You know, the stuff from what we actually get real "meat". Here's a hint - "real meat" tastes exactly like "real meat". Just like mankind has been eating for millennia.
There is definitely an issue developing around that. It's called "too much of a good thing". You should read a little on the environmental impact that "too much livestock" is having on our environment. We crossed the threshold quite awhile ago. The effects are measurable now. The numbers and the effects are not pretty.
Most people I know who've educated themselves on the topic now advocate for a significant reduction in livestock. And a shift to "grass feeding" beef, and others, from "grain feeding", which also drains resources without really providing a lot of benefit.