7. Migration, again - Since it took so incredibly long to get to Windows 7, what is the organization's tolerance to undertake another migration? Is IT prepared to jump into it? Have you evaluated all of the facets and ramifications? What projects are waiting and will be postponed if you move to Windows 8? Do you have the resources for another migration? Will you see an ROI with yet another migration so soon? Most organizations are suffering from "migration fatigue" and don't have the energy, and ultimately lack the cumulative political will to undertake the entire process again.
8. The unknown - The last, but most important, reason not to race to Windows 8 is that no one knows what Windows 8 will really be when it is released. We have a very, very early release of the product, which was really only provided to get the ecosystem of hardware OEMs and ISVs, a group Microsoft depends upon to make Windows successful, working on making their products work properly with Windows 8. There is a whole flywheel that has to get spun up for Windows to be successful. If you choose to be a part of that spin up, expect it to consume a lot of time and money as you join the OEMs and ISVs who are developing and refining products and tools to run on this exciting new platform.
Read more about windows in CIO's Windows Drilldown.