In a world of 7+ billion, it seems clear that the earth will not be able to provide humanely raised local meat for everyone who wants it.
It seems to me there are two scenarios for the future of meat eating, both bad. The first follows an organic or family farm model of farming, with organic meat becoming a bespoke, cheffy commodity in demand for the rich. While the worst excesses of animal confinement are controlled, demand is never ending as people see meat as a marker of wealth and upwards mobility. In this instance large amounts of land and resources in poorer areas of the world are commandeered for meat production, leaving only poor quality land for subsistence crops for locals and leaving vast population vulnerable to periodic starvation. Economic pressure on meat production never really goes away as even the very rich are conscious of price, so animal welfare shortcuts are always considered.
The second scenario is that billions more animals are confined into concentrated animal feedlots to provide cheap meat for a burgeoning world market. This causes environmental devastation and untold suffering for animals. It also creates negative outcomes for people's health, with a growth in diseases of affluence along with great risk of pandemics.
What if we all ate plants? Would there be more to go around for everyone? Some argue that meat production is a good use of marginal land otherwise unsuitable for agriculture. But it seems to be that there are many other uses for marginal land such as sustainable forestry, carbon sinks and wildlife reserves.
By all accounts, the demand for meat consumption grows with industrialisation and economic growth. That is, unless there a counter demand for plant based foods arises. It seems to be that being part of that counter demand is a worthwhile aim.