For what windows does in the real world, other companies already do better and most importantly cheaper. games? steam is a household name.
I never did get it to work on Linux, on the very same machine on which it worked on Windows. Just always gave me a network failure. No firewall rules on the Linux box, same rules on the gateway, same IP. No uPnP. Windows is ten times the household name that Steam is. Virtually no AAA titles run on Linux, so you neeed Steam and Windows to play them.
word processing? a google docs enabled chromebook has that covered in spades along with social networking and internet.
Yes, but it doesn't actually deliver a better experience there; you have more flexibility on Windows. Sometimes a site craps itself in Chrome, I have the option to load up Firefox.
Windows is still compelling for gamers especially, and for people who run professional applications. It's true that chromebooks will do for most people who only websurf, but don't count Windows out yet. Especially for all those AMD GPU users, for whom the Linux driver is shit.