Meat is less efficient but only by a factor of 10 or so. Unless food costs as a proportion of income go up a huge amount it is unlikely people will not be able to afford meat. It may well become less popular. Even well cared for animals are not that much more expensive.
No cite, but even if true. That is today. Things change. Increasing demand for land and water, increasing demand for meat by formally poor peoples in rapidly "industrializing" China/India will skyrocket cost.
