Microsoft’s Satya Nadella has confirmed that the next version of Windows, probably Windows 9, will unify the Windows, Windows Phone, and Xbox operating systems into “one single converged operating system.” Microsoft had previously made some moves towards unification with Universal Windows Apps that run across all three platforms, but this new version of Windows will go a lot further: “This means [we’ll have] one operating system that covers all screen sizes.” The question now, of course, is whether this will be the one-Windows-to-rule-them-all (and in the darkness bind them) that Microsoft desperately needs in order to stay relevant in a rapidly shifting personal computing environment, or whether it’ll just be a jack-of-all-trades-master-of-none flop — a bit like Windows 8.

Way back in June 2012 I called for the unification of Microsoft’s operating systems as an answer to most of the company’s woes. Even though Windows 8 hadn’t even been released yet, Windows Phone 7 and its Metro interface had already lead ballooned, and a lot of angry words had been spilt over the death of the Start menu and the introduction of Metro in Windows 8. A single operating system that leveraged Microsoft’s biggest advantage — its huge Windows developer ecosystem — while at the same time building a unified user experience across all platforms and screen sizes seemed like a surefire way of ensuring the success of both Windows Phone and Xbox, and the continued survival of Windows. Microsoft might have actually stood a chance against Android and Apple smartphones and tablets — but instead it frittered away much of its user base and positive mind share through the fracturing and alienation of its different platforms.

Over the last year — probably since Windows chief Steve Sinofsky was forced out of the company — Microsoft has been gradually dropping hints that, yes, it dropped the ball, and that convergence was once again on the cards. The first step was to combine the Windows 8 and Windows Phone 8 app stores, and after that the plan was to create Universal Windows Apps — apps that developers could write once, and then run on any Microsoft platform (Windows desktops and tablets, Windows Phone smartphones and phablets, and on Xbox One in the living room). Just last week, Microsoft merged the Windows and Windows Phone developer portals.

And now, during Microsoft’s quarterly earnings call, CEO Satya Nadella has confirmed that “We will streamline the next version of Windows from three operating systems into one single converged operating system for screens of all sizes.” Presumably he is talking about Windows 9, which is due in spring 2015 — but I think that would be a very aggressive timeline (unless Microsoft has already been working on this convergence for a while). Another option is that it’ll be Windows 8.2 in spring 2015 with the return of the Start menu, and then the unified Windows 9 coming later in 2015 or 2016.

The big question now is whether one big Windows operating system across all platforms and screen sizes is actually a good thing. Assuming that Microsoft can deliver some amazing developer tooling to allow for slick, cross-platform apps, then I can definitely see this as a good thing for the Windows Metro, Windows Phone, and Xbox One ecosystems. If an indie developer can make one game that works well across desktops, tablets, smartphones, and consoles, then that can only be a good thing. Likewise, this would go a long way towards making Windows Phone a primary target for developers (there are still many top-tier apps missing from the store).

Beyond unifying the apps, developer tools, and app stores, I’m honestly not sure what form this “converged operating system” will actually take. All three of Microsoft’s major operating systems already make use of the same Windows NT kernel, along with some other low-level libraries. How much further can Microsoft actually take things? Given how a variation of the Metro interface is already used on Windows Phone, Windows 8, and the Xbox One dashboard, maybe this convergence will finally standardize the Metro Start screen across all three platforms, with the same settings and options for all devices and screen sizes? We certainly won’t see the classic Windows Desktop rolled out across Windows Phone and Xbox One, that’s for sure.

On the same earnings call, Nadella said there’ll still be segmentation by SKU; you’re not going to buy a single copy of Windows that you can install on your laptop, smartphone, and game console. Puzzlingly, he also mentioned that “converged Windows” more refers to the fact that there’s going to be just one engineering team, and that they’re going to “approach Windows as one ecosystem.” There is clearly some confusion about just how converged Microsoft’s operating systems are going to become.

In any case, no matter how the engineers actually go about achieving convergence, the main thing is that Microsoft must provide a compelling user experience and bountiful app ecosystem across all platforms and screen sizes. I’m not convinced that unification is necessarily the best way to do it (Apple still manages to do it with iOS and OS X, despite keeping the OSes fairly separate). But, faced with almost zero mobile market share, no obvious route towards regaining consumer market share, and the need to do something dramatic following Nadella’s proclamation of a new vision and direction for Microsoft, it seems convergence is the risky path that will be taken. Stay tuned: If you thought the introduction of the Metro Start screen in 2011 was contentious, I think the next few months, as Microsoft unveils the unified Windows 9, will be even more dramatic.