Jeff, thanks for your thoughtful reply!
I imagine a very considerable percentage of meat-eaters will never give up their animal - based diets because they love eating meat, they're culturally wedded to it, and they see it as natural as breathing.
We also have a percentage of poor rural dwellers (about 70% of 880million people) who rely on their livestock for their food security - that's about 650million people who have no alternative to eating meat, because they don't live near a Lidl with three types of veggie sausage on offer.
So between the ones who won't go vegan, and the ones who cannot because of their life situation, you have the ones who could and would. It's here that change could be made, potentially. But as I mentioned, more pork and more chicken is eaten now than last year, but not as much as next year...
China hasn't even reached its peak meat consumption yet...how do we even start to convince them that animals have feelings?
Edit: I don't do maths or percentages so my workings out might be wrong...