If the ergonomics of a tiny screen, keyboard and trackpad weren't enough to convince you that netbooks will cease to be the phenomenon they were as tablets come into play, just look at the results of this study.
Polling a sample size of "over 1,000 distributed across gender, age, income and location in the United States," Retrevo found that, of people who'd considered buying a netbook last year, 30% ended up buying an iPad. (40% bought the netbook after waiting to see the iPad unveiled, while the remaining 30% bought a netbook without taking Apple's plans into account).
Keep in mind, the iPad was most probably a $200 upsell to these netbook shoppers, or more.
I don't think that these results alone are enough to proclaim the iPad a runaway success. But of those who were initially attracted to netbooks (I assume Retrevo meant, rather than a laptop), the features people found most enticing were "portability", "price" and "battery." In other words, if the iPad drops in price, it could be set with other important criteria.