I didn't make light of the question, I just pointed out that it was kinda dumb. The world becoming vegan will take years and years to happen. It starts with less demand for animal products, then less will be produced. Like I said, it wouldn't happen overnight, so your justification for eating animals in order to control their population is not a valid one. I'm sure you have plenty of other excuses though.
So, what becomes of cows? Do we put them is Zoo's, make them pets... You act like the billions of cows will magically become just a few thousand by virtue of creeping veganism. That is more than kinda dumb.