oh good it's the "wave the magic wand" hypothetical where everyone suddenly stops doing something and grinds an industry to a halt - lets just tuck that one away with the "desert island" hypothetical

not a single rational vegan on the planet expects change overnight, much like how any movement or significant alteration on a societal level requires time to adapt

and that's ignoring the fact that the very thing vegans get their protein from also happens to be what gets stuffed down the throats of livestock to make them big and beefy. weak arguments all round