By the way, this is a different model from Apple's model of the iPad as a device that lets you do cool stuff.
And again, there are a lot of people who don't have tablets, and people who do not have smart phones or the latest computers. And there are people who may just want a super ebook reader with extra features. There is not a small or monolithic market. Lots of room for everybody. So again, while Apple may not have to worry, they, and everybody else, needs to pay attention to successes and failures. If Amazon comes out with a good product, things could get very interesting for all the other players.
As an aside, momentum doesn't mean much, either for software or hardware. Not too long ago, everyone was on MySpace in between using their Blackberries. Today, not so much.