You know, I'm sure everything you said is right, nevermind the lack of citations or supporting logic for why this would actually be the case, instead of wishful thinking. Let's say it's all true.
The whole point being made here is that bacteria evolve very quickly, and trade genes with each other as a part of that. Bacteria doesn't reproduce sexually like we do; In fact, they happily cannibalize each other for genetic material. It doesn't do this intelligently, but it does do it very, very quickly. So the bacteria in your mythical "animals only" sphere of influence can and are cannibalized by the "humans aren't animals" category of bacteria. They cheat, see... they don't follow your nice little boxes you've built here.
Bottom line is your distinction is arbitrary and does not exist in nature. And antibiotic resistance isn't a 1:1 parity either... if it's even partially effective against, say, penicillin, it probably is effective against others as well. And as more of these genetic markers come together, not only does the bacteria become stronger against antibiotics as a whole, but because more and more of the bacteria has those markers now, there's a greater chance of transcription, mutation, etc., that will create an even greater resistance.
The fact is the biological clock is ticking. Even in the most optimistic case where everything you say is true and then some, it only delays the inevitable. What your post amounts to is basically apologism for the overuse of antibiotics to drive profits in unrelated fields, when they should have been kept strictly for use as humans, and not animals or livestock. The very day the first antibiotic was created, the so-called "miracle drug" of the 20th century, we knew this would happen.
We just didn't give a fuck. We ignored science because it meant prosperity today... but a terrible price later. And if anything defines western civilization today, its short-term gratification at the expense of long-term growth and prosperity.