I don't think that ChromeOS presents any real challenge to Windows, except in the Netbook market.
Even so, as a CR-48 user, there's still quite a bit lacking (a recent HN thread, "No Skype on ChromeOS" comes to mind.)
Windows, OSX, and various Linux releases all work great as development environments. ChromeOS does not. ChromeOS also is designed to be a partially-featured OS - it has just enough OS parts to basically get the Chrome browser running.
It's interesting to consider people switching over to a more cloud-centric style of work, but honestly, I don't think ChromeOS will be replacing or even challenging Windows any time soon.
Yes, it will be a little while, but it will be inevitable. All Google has to do is to produce a free installer for netbooks. Then students from middle high school on up will download ChromeOS and slap it on used netbooks and have all of their software and communication needs met for free.
If ChromeOS can deliver on seamless sync everywhere and use NaCl and Gears to lessen the offline pain, then you're going to have an entire generation growing up on cloud computing.
EDIT: The seamless sync + the communication is key. Such tech savvy kids are also going to be using the iPod Touch and its ilk as mini tablets/social media communicators. If there is enough integration across all these devices, ChromeOS can hook those kids and keep them on a cloud computing use pattern all their lives.
NaCl has nothing to do with offline web apps, and Gears requires a browser plugin while HTML5 solutions do not. But some form of offline access would be great in any browser until data plans become as ubiquitous as home phone lines.
But I'd love to run offline native apps with it. All of those photo editing apps NaCl is supposed to make snappy? I definitely want to run those offline.
Gears requires a browser plugin
Google controls the distro!
while HTML5 solutions do not
It doesn't matter how it happens, but mitigating offline pain will be a key factor in hooking the next generation of users on cloud usage patterns.
I don't think that ChromeOS presents any real challenge to Windows, except in the Netbook market.
Even so, as a CR-48 user, there's still quite a bit lacking (a recent HN thread, "No Skype on ChromeOS" comes to mind.)
Windows, OSX, and various Linux releases all work great as development environments. ChromeOS does not. ChromeOS also is designed to be a partially-featured OS - it has just enough OS parts to basically get the Chrome browser running.
It's interesting to consider people switching over to a more cloud-centric style of work, but honestly, I don't think ChromeOS will be replacing or even challenging Windows any time soon.