Why the presumption that this must be an "Android tablet"? Amazon is one of the few companies entering the tablet market that isn't a primarily a "computing device" company. They have a computing device product, the Kindle, but it's very focused.
Amazon is an online:
* media retailer
* department store retailer
* book seller
* catalog warehouse (third-party resellers)
They have broad distribution agreements with thousands upon thousands of merchants in all product spaces (including media). No other tablet manufacturer (not even Apple) has the kind of vertical reach that Amazon does.
Amazon is also a pioneer in understanding the way their customers shop for products. Amazon's iOS apps are some of the coolest shopping applications I've used. Scan a bar code of a product at a store, and instantly find out if you can buy it cheaper on Amazon. Usually you can. That's smart. They constantly refine their website to fit customer usage patterns. They know how their customers behave, and they know how to adapt to customer change.
Remember when the iPad came out and geeks everywhere united in sentiment that it would fail. "It doesn't run a full desktop, OS!!! It's doomed to fail!!!" That's a caricature of tech punditry at the time of the iPad launch. Today, the iPad is way out front. All those arguments sound eerily familiar to:
"If any API incompatibilities emerge (beyond the normal API level that Android uses to distinguish between release APIs) then developers will be forced to fork their own products and maintain 2 separate release channels..."
This is all geek speak. Turns out, the market doesn't really care.
Amazon, like Apple, isn't trying to enter a market, they're trying to create one.
I'm not smart enough to know if they'll be successful, but if you look at Amazon as a company, they're an entirely different animal from Apple, Google, or Samsung. I think they have the tools to make it happen, but it will ultimately come down to execution.