operating system Microsoft will ever put out will be more of a "market success" then Windows 95 was. Windows 95 made the Windows monopoly. All Windows 7 could possibly do is "maintain" the status quo.
But anyway I don't think Windows 7 will reverse the downward trend of Windows's dominance. I think in the future OEMs will have a much bigger part in the development of software, kind of like how it was before the Windows monopoly. Stuff like the HP Mini netbook
and Dell netbooks are evidence of this.