I'd love to see the retail sales figures vs. the number of copies licensed through Volume Licensing and other Enterprise Agreements.
Yes, Windows 7 is all pretty like OSX now. Ubuntu is a great alternative in some cases. Does the average corporate care? No. They are more concerned with licensing, ease of deployment, manageability, compatability etc.
Windows 7 (and in some cases Vista) allows activation via a KMS Server, BranchAccess for Remote Access, new Group Policy features, BitLocker etc which go largely unnoticed by the average desktop OS "deathmatch" but which are a major differentiating factor to a corporate buyer. XP Mode (XP in a VM) is a packaged workaround for those companies still using that old accounting app bob's nephew wrote 12 years ago which runs the entire business. I am not saying there are no alternatives and I'm sure next year will definitely be the year of Linux on the desktop.
I'll admit my view is entirely skewed as I've never had to pay for MS Software (working in IT you rarely do due to work arrangements) and use it/deploy it as a job but the desktop at home is not the be all of an OS.
Personally I have dealt with a number of customers planning SOE deployments of desktop refreshes and plan on using Windows 7. The fact that XP is in extended support turns a lot of customers off deploying it fresh on a large scale. Vista is effectively dead in the water for all but the few who have already begun deploying it.
I'm sure there will be the fanboys out there on release day queuing at stores to get it, but Joe user will probably get upgraded when they buy their next PC from the local electronics store.