I could see them doing something in the Android tablet space that is worthwhile, and there actually seems to be some growth there. Maybe I'm the only one, but I just don't see a future for Chromebooks. They aren't that much cheaper than a cheap laptop, and the limited offline functionality doesn't seem to serve people well in the real world. I'm sure I could be wrong, and only time will tell.
When recommending them to people who need something cheap and "virus free", I make sure I'm very clear that they have incredibly limited functionality. I essentially describe them as a tablet but with a proper full blown browser.