No futuristic films have come true when they try to predict society changing - ideas and beliefs are passed on from generation to generation. Food is much more sticky since meat-eating humans are likely to feed their children meat. When they come of age to understand things like veganism (beyond "vegans choose not to eat meat"), the fact that they've been eating meat for years will play a large part in whether or not they even consider taking on those new morals.
vegetarians choose not to eat meat. vegans choose not to consume animal products, e.g. often also avoid leather shoes and similar products not necessarily limited to food
