This is a very common argument and it's a little shortsighted, because the answer is broadly "yes". Reducing the number of cows/chickens/etc in the world is a net positive, and would only require us to stop force breeding them like it's some kind of degenerate poultry hentai. Allowing the species to reduce in population is only of benefit to the species (cough humans cough) and is overall desirable. Keeping some in zoos would be fine, maintaining the native wild populations is also a good plan, small scale farms ("family" or "hobby") farms where they don't brutalize the animals is also a feature of most vegan utopias. Take india, where most of the population is vegan: there are still cows on farms, cow-derived produce is still available, it's just the cows aren't kept in American-style stock farms.

YMMV, and like any ideology there are other opinions with equally valid outlooks, this is just what I see most often. (full disclosure, I am not a vegan (there's plenty of evidence to that in my post history), I just sleep with a lot of vegans and quite like chana masala)

(There's also a pretty... sane... subgroup that proposes 'corrective breeding'; a process wherein we undo the destructive changes humans introduced to the species and return them to what would be found in their 'natural' state. "Contentious" is probably the best description.)