I think that's why Amazon will do better than other tablet makers. Because they are NOT going after the iPad. They are offering something with fewer features, but much cheaper and still with a great selection of content.
Most other tablet makers are going after the iPad, and they fail the comparison every time. Why would you buy a playbook or TouchPad (at full price) when you can get an iPad for about the same price or a little bit more?
Apple has content to sell hardware and Amazon has hardware to sell content, and so they can attack this market from different angles and be differentiated enough to both do well. But if you are trying to compete with Apple yet have worse hardware and worse content than they do, why would anyone buy your stuff?