This article was interesting talking about apple's dominance with the iPad. They don't believe its going to last as long as people think. I know for someone who has a sister who works at the apple store, she would be happy if the lines for the iPad and new products calmed down just a little bit. I definitely think the iPad will continue to be a hot selling product and dominate the market until a competitor comes up with something better.
Source: "Nielsen numbers show iPad dominance slipping," RCRWireless Unplugged