Microsoft's Windows future: One core, many SKUs

Is Windows RT dead? Is the desktop going away ? What's 'Threshold' got to do with it? Here's my latest attempt to try to make sense of where Microsoft's Windows roadmap will lead in the next couple years and beyond.
Written by Mary Jo Foley, Senior Contributing Editor

Recent remarks by a Microsoft exec who noted there won't be three different Windows variants in the future have set off a storm of speculation  -- just about all of which is dead wrong.


Microsoft Executive Vice President Julie Larson-Green recently told attendees of a UBS technology conference that Microsoft was not going to have three different Windows SKUs (Windows Phone, Windows RT and Windows 8.x). She didn't say how many Microsoft ultimately plans to have, but some believe the answer is one, given Microsoft's "One Microsoft" mission and creation this year of a unified operating-system engineering team.

I've seen folks claiming Larson-Green's comments mean Windows RT is dead. I've seen others claiming Larson-Green's remarks mean the Windows Desktop is dead. I've seen another group claiming she was conveying that the Windows Phone OS is dead.

Larson-Green didn't actually say any of those things. (You can read her exact words in this transcript.)

One core, many SKUs

So what did Larson-Green's remarks mean? In my view it's not exactly "One Windows," as my ZDNet collealgue Simon Bisson recently described it. In reality, it's a bit more nuanced. It's more like "One core and many SKUs" -- the lot of which Microsoft plans to call "Windows."

Microsoft has been on a journey toward this new approach for a couple of years now. At the start of this year, Microsoft brass were talking publicly about the ability to "write once, run on any Windows."

The Windows NT core is now the heart of Windows Phone 8, Windows 8, Windows RT and the Xbox One operating systems. These platforms share some (but not all) application programming interfaces and developer tools. (I've heard talk that only about a third of the Windows APIs are currently shared between Windows RT, Microsoft's ARM version of Windows, and Windows Phone OS which runs on ARM.)

As Microsoft completes its "Blue" wave of deliverables with the Windows Phone 8.1 "Blue" release in the spring of 2014, the company will inch a step closer toward enabling more Windows APIs on Windows Phone. A complementary (and complimentary) update to Windows 8.1 will help with this on the Windows side.)

Then, with "Threshold," the next Windows wave following Blue, which starts rolling in around Spring of 2015, Microsoft will enlarge the footprint of the common Windows core shared by phone, tablets, PCs and entertainment console even further. The goal is to make sure all the flavors of Windows share more in terms of foundational infrastructure, i.e. the same file system, driver model, memory manager, application platform, app store and services.

I wouldn't be surprised to see Microsoft, in the not-too-distant future -- possibly even before Spring 2015 -- start calling all its variants of Windows just plain old "Windows" (even though they won't exactly identical).

Windows SKUs, or versions, will continue to differ based on platform: Phone, phablet, mini tablet, tablets, laptop, desktop PC, console. Some of these form factors will run a single "Windows" SKU; others will offer customers a choice of two (such as Home and Pro in the case of PCs, for example). The difference will be in the UI/UX (user interface and user experience). In other words, the Windows that runs on your phone won't be the same Windows from a look, feel and/or use perspective, that runs on your Xbox One, or even your ARM-based tablet.

There are some obvious questions here: What about apps and backwards compatibility? The goal, no doubt, is to make sure there's a support story for the existing Windows Phone and Windows Store apps that users already have purchased and downloaded. Exactly how and if this will happen, I'm not sure. The hope seems to be that developers will be able to create the bulk of "modern"/Metro-Style/Windows Store apps once and then target particular types of devices, whether they be phones, mini tablets or All in Ones.

Another question: What about the desktop environment that allows users to run existing Win32 apps? When does it go away, if ever? Talking to my contacts, I believe the answer is not anytime soon. A big part of the reason: Microsoft wants and needs Windows XP and Windows 7 users to be willing to move to Windows 8. That means the desktop, desktop/laptop PCs and mouse/keyboard support aren't going anywhere for the forseeable future.

How will Microsoft differentiate Windows SKUs that include the desktop environment and support legacy Win32 apps from those that don't? That's the million-dollar branding question. Windows RT was not the answer, as Larson-Green herself recently conceded. 

Bottom line: This transition won't be complete next year. Or even the year after. And the end result will likely be neither as simple as a single Windows SKU, nor as complex as 10 largely different flavors of Windows.

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