Michael Scalisi doesn’t think Chrome OS is a threat to Windows:
By completely omitting local apps and storage Google made it obvious that it’s not looking to replace your existing OS. Pichai acknowledged that not all apps will run on the Chrome OS and countered that “most people who buy this device next year…expect them to have another machine at home.” As my colleague Robert Strohmeyer pointed out last week, Chrome OS seems intentionally unremarkable. This demonstrates that Google isn’t positioning Chrome to take over as your media center, gaming machine, or professional workstation.