Where's your proof OP?
This is a very controversial subject, even among doctors, from what I've noticed.
I don't think that all people can survive without meat. If you want to stay healthy and fit (and exercise) you need the protein the meat has to offer, I personally think we are in fact meant to eat meat to survive.
I'm not trying to offend any vegans/vegetarians - eat whatever you want to eat, but I personally don't think humans can get enough proteins and nutrition in a meat-less diet, unless they use stuff like powders and supplements.
I'll give you an example - me and my cousin. I like eating meat, my cousin is vegetarian. We go to work out together, she gets tired and leaves around 20min before I do. Which is normal, considering what she eats. To have energy, we need meat. Of course you can get energy from carbs too, but they're not nearly as healthy for you as meat, as the body processes them a lot slower or it goes straight to fat.
I don't think we'll ever be in a place where humans don't eat meat. Unless some replacement is made. It's nature. This is how it's meant to be.