Those who sow...
Microsoft are now reaping the results of the decision they made back in the 90s to eschew the traditional software upgrade model of major and minor version releases in favour of presenting the world with a brand new (apparently) product every few years, and thus forcing users to shell out for a complete new product, rather than a more moderate price for a version upgrade. If they had taken a staged approach with the WInNT development stream, we might have seen:
Windows 5.0 - 5.4 (aka Win2000)
Windows 6.0 - 6.x (aka WinXP)
Skip Vista entirely
Windows 7.0 (Win7) - Windows 7.5 (perhaps) (Win8).
What we know as XP would by now be only one major version behind, and open to additional development and/or maintenance, rather than three products behind, and politically embarrassing to develop further.
Microsoft has sown the seeds of its own decline with its grasping business practices, of which this is only one example. Similar comments apply to the Office range of products.