Meh, this thing will probably sell around 10 million units this year. Next year you will get a 32gb with a front facing camera and and some other spec bump (battery to 12hrs, processor boost, or sd card slot built-in) for $399. The OS will also advance further, and it will be able to do 90% of the things that a desktop can do, and 99% of the things that most people use computers for on a daily basis. Larger developers will begin jumping on board, including some from the PC world. Mac market share will increase a little bit more, iPhones will be selling like hotcakes, and Apple will be fine just like they are now, but closing in on $50b cash reserves.
I'll be buying the 32gb Wifi iPad for college use, and in two more years, a 3rd gen 256gb iPad with 4g wireless that (maybe) uses that Apple patent with a solar charger built into the screen/bezel as a college grad present to myself. I'll then gift the old one to my grandparents if they haven't purchased one yet.
Interesting to note that at my school, Missouri State University, in the design program, there are many students who are excited about getting an iPad. Though these are already Mac users for the most part--except for maybe two, one of which has an iPod Touch. My wife is also interested in getting one eventually, and her only Apple experience is my first-gen iPhone that she uses as an iPod Touch. I tend to believe that most people won't buy one right away, especially in this economy, but are looking to pick one up sometime in the next year. Especially once any potential bugs are worked out and the OS is updated to 4.0.