AWS and Amazon are a perfect pair. AWS makes lots of money, Amazon provides a perfect tax shield due to it voracious appetite for capital. Kahn's goal here is not some trivial thing for the consumer's benefit. No, Kahn wants to break up the Amazon side and destroy that tax shield. Because if that tax shield is gone the Feds can take billions out of AWS in taxes. Since there are no legal grounds to split AWS off from Amazon, the alternative is to break up Amazon.
Breaking up Amazon will satisfy the goal of destroying the the tax shield. But the downside to this is that those shattered pieces of Amazon are all going to lose money and be capital starved. I don't see how Amazon delivery, or Amazon advertising, or Amazon's store brand or Amazon Prime video can all operate as standalone entities. The whole Amazon system relies on a web of synergistic support. The combined whole of Amazon is greater than the sum of its parts.
So who will end up winning from breaking up Amazon? The answer is obvious. The government gets a pile of new taxes and Alibaba gets a pile of new customers. Hundreds of thousands of Amazon employees all lose.