To me, this is simple. Everyone in my family sits down at the computer or picks up a laptop, logs on and runs Firefox. That's pretty much it. There are only rare exceptions where they do anything else. I don't think anyone plays any games on computers that aren't on-line. The biggest exception to this I know of is some music editing like Garage Band.
I personally only use the browser, Chrome on Windows or Firefox 3, and a terminal program. That's more than 90% of my computer usage. The occasional exceptions are Fritz chess and MS Flight Simulator. At work, I use Firefox and xterm windows. That's it.
For me, if there's a good terminal app that runs inside the browser, then I'm pretty much done.
Thus, it makes perfect sense to shave off everything else and make a system that's only the browser and nothing else. That's all. And at the same time, make it faster and more secure.
This is not going to be a server OS. I'll personally still need Linux boxes for that.
The implications for the corporate desktop are huge. Hopefully everyone is already using on-line email and probably most corporate apps are on-line. If you can get everyone to use on-line office apps for word processing, spreadsheets and persentations, then you're done. Desktop maintenance as a function is gone. Everyone has a Chrome OS system, or something like it. The IT Crowd fix, “Did you turn it off and turn it on again?” will literally become the only solution to a problem except for replacing the computer.
And no, there's no reason you can't do this now with careful paring down of a Linux distribution.
I think the biggest dilemma may come for someone like me. I have this suspicision that Chrome OS may be so much better as a browser, I'll have to choose between booting/running it and regular Ubuntu which I might want for some other purpose. Yes, I know Chrome will run on Linux but I have this idea that the user experience will be different enough to make, uh, a difference.