I certainly agree with Merc had to say on this.. they have transitioned to a utility and not a driver of technology.
However where MS will struggle is the transition of the wider paradigm of the switch back to centralised services, eg the current trend back to the mainframe/terminal setup that was common in the 60s/70s, but it's in the form of SaaS in the cloud and thin clients (aka web browsers) today.
The marketing people will make us believe OpenStack or similar infrastructure will prevail, and iOS and Android devices are the new mass media consumption devices. Certainly in house servers and desktops won't go away, but I can certainly see a scale back on the number of Windows based solutions compared to others. Heck, even MS pushing their cloud servers with Windows 8 (SkyDrive, Outlook.com) could be a doubled edged sword, as all these services are available via other non-MS devices. How much does one really need Windows, if pretty much all you do is online? (GoogleApps, GMail/Yahoo/Outlook, FB/MySpace/Twitter/what-ever-flavour-of-month-social-media).
Their next CEO certainly has a very large boat to steer in what looks like an upcoming storm. (Or put in military terms, a Colonel is given a large militia battalion in the Wild West, but the Indians are already on the door-step). Will the next CEO after Ballmer be a scapegoat for Wall Street to rag on, even though in many peoples eyes, it was Ballmer's doing for the current trend of large anti-MS sentiment in relation to Win8?