Sure, everybody reducing their meat consumption to their share of what is produced on marginal land would be the optimum, even better than everybody going 100%

Sure, everybody reducing their meat consumption to their share of what is produced on marginal land would be the optimum, even better than everybody going 100% meatless. How much of the typical meat consumption of a current-day nonvegetarian would that be? 5% perhaps? And it wouldn't be the same 5% that we see with "almost vegans" today who argue "less but better" to only eat premium cuts while proudly announcing that they avoid all grinder meat. If you want to eat the steak, don't scoff at the sausage. Back to grazing marginal lands, yeah, I'd also hate to see the animal species that have accompanied us throughout human history go extinct. But we're very far from that.