Well, from a corporate standpoint, I can honestly say I don't know of any IT managers who would be very willing to scrap hundreds of thousands, perhaps millions, of dollars in existing hardware just to continue an upgrade path. It is just not cost-efficient, and your ROI is non-existant. If these new systems break it is not a simple matter of pulling a hard drive out of an old system to keep it running or swapping a video card out from one in the cage in the IT shop. It requires whole new service contracts with hardware vendors, and whole new software contracts with Microsoft, which I can honestly say people are getting tired of shelling out millions of dollars for.
The organization I used to work for as a Systems Analyst shelled out 1.5 million in Win2K Pro and Office 2k licenses, not including the hundreds of thousands in new servers, desktops and workstations to handle the jump from the existing Banyan/NT environment. Add in to that the money for licenses for GIS, AutoCAD, engineering applications, etc. Having to now look at scrapping that to build essentially from the ground up in Longhorn? Hmmm.... open source looks better all the time...
Linux (and even Apple) might be wise in taking advantage; however, I hear Apple is dropping backward support of OS9 now... Interesting times ahead...