It's a pretty ridiculous simplification of how nature works. Animals being dependent on each-other is found everywhere in nature, and the fact is that cows at this point would stand almost no chance in nature since we have bred them to the point of cuddly teddy bears. So you could argue that cows get protection and we get milk, it's not necessarily exploitation in my mind until you get to the point where you talk about industrial production of meat and dairy, which to be honest is pretty cruel and horrifying in parts.

> Animals being dependent on each-other is found everywhere in nature

Human ethics clearly shouldn't and aren't based on what other animals do to each other though.

> the fact is that cows at this point would stand almost no chance in nature since we have bred them to the point of cuddly teddy bears

You could justify anything with this argument: "doing X to Y is bad, but we've specifically bred Y to have X done to them such that Y can't survive in the wild anymore, therefore it's okay to do X".

Just stop breeding them. There's related species in the wild that will live on.

Sure, from a vegan perspective you can stop the entire meat and dairy industry completely based on the fact that it's not strictly necessary for our survival, but a lot of things aren't strictly necessary for our survival. You can also argue that humans have an ethical responsibility to be "more" and that because of this we shouldn't consume anything that causes suffering in living beings. Both of these arguments come out of personal ethics though.

In ethical terms, most people simply do not feel that the suffering of animals is equal to that of humans. One may not agree with this, but it's why people eat meat in the first place, or accept animal testing for medicine. So, as long as "specism" is the reigning morality that people subscribe to, it's unlikely we'll see a vegan wave, unless perhaps there's a climate component driving it as well.