But it's important to remember that Forrester's survey was carried out before any Windows 8 tablets had been released, and there's still a risk that people will reject Windows 8 on tablets the way they seem to be doing with Windows Phone devices. If neither of these platforms take off then Microsoft will be left with a desktop operating system with a user interface that has no reason to exist -- one that has been adopted to match a tablet and phone user interface that no-one is interested in. "If enterprises are slow to adopt Windows tablets or don't see the value proposition then that whole strategy is at risk," Johnson says.
This view is echoed by Michael Silver, a research vice president at Gartner. "If Windows 8 on the phone doesn't take off then it's really no big deal for Microsoft. But if they do poorly with the tablet this has much bigger implications." The only driver to deploy Windows 8 at this stage is to provide a unified operating system for tablet and PC users, so if Windows tablets fail to take off then that driver disappears, he adds.
The barriers to adoption of Windows 8 would remain, however: A new interface means a new way of working, and probably a certain amount of training or experimenting before productivity levels return to pre-Windows 8 levels.
"The new user interface is less of a problem than it would have been ten years ago because people have got used to mobile interfaces, says Johnson. "But our surveys show that companies are concerned about this, they don't think the user interface changes are good changes."
Perhaps what Ballmer meant with his "all-in" comment was simply that there is no going back from the changes that Windows 8 introduces: If Windows 8 fails, there will be more of the same, including the new interface, in Windows 9. "Windows 8 should be seen as the start of a journey," says Michael Cherry at Directions at Microsoft. "The current Windows code is now 20-years-old, so for Microsoft doing nothing is just as risky as attempting to introduce the new Windows. At some point they really do have to get off the old plumbing," he says.