I'm not sure I would call a netbook a "full fledged computer". Sure they can do all the basic stuff, like web browsing and word processing, but their specs are too weak to handle many programs. Plus they don't even possess an optical drive unless you purchase an external one.
More on topic though I think the electronic reader is here to stay. They probably won't remain single function devices however, but rather implement things like basic internet browsing and note taking. Much like we're already starting to see with the Kindle and iRex products. The technology will improve as well... eInk's refresh rate gets faster with every iteration, and eventually we'll have color. They may never be as functional as netbooks, but then there has to be some sort of trade off for weight, battery life, and daylight viewability advantages.