I don't guess Chromebook will see any success.
Well, let me define the factors for my so called thinking..
1. Data Security : We don't know how secure is our personal data on cloud. I don't think people would like to share their everything with google or store them on some server. What if the server gets hacked or so?? If people starts doing that, hackers will surely try their best to hack the Google's server.
2. Connectivity : The OS is totally cloud based, so internet connectivity and speed is the main thing here. Specially on 3rd world countries. So you can't count success without them right?? And you need internet everywhere over the world, to make Chromebook successfull. What if someone from UK / US (where internet conenctivity is not a factor) comes to India or other developing countries and he uses Chromebook??
3. Applications : Are you sure?? Every kind of app is available?? And if yes are they good enough to compete with the desktop(windows/linux) apps?? I mean yes, enthusiasts can always look for alternatives. But in production environment / Enterprises. I'm 100% sure no one would like to leave Photoshop, Dreamweaver etc. if the alternatives are not even close to them.
Well, these are the main three issues I can think of right now, which makes a hurdle for moving into a Cloud OS completely.