For the past several years, Microsoft has delivered its new Windows client and server releases in tandem. But with Windows 10, Microsoft is going to deviate from that practice and postpone its next release of Windows Server until 2016, while its complementary Windows 10 client will roll out in calendar 2015.

Microsoft officials confirmed the decoupling of the coming client and server releases in a blog post on January 29.

There had been rumblings from my sources, as well as Windows IT Pro, that the coming Windows Server release might be delayed.

Today's blog post doesn't explain why Microsoft officials decided to take this new path. I've heard a few theories. Some believe the next version of Windows Server includes more bugs than Microsoft officials deemed acceptable, leading to a delay in the second public preview from the previously promised "early 2015," to "spring 2015."

Others from whom I have heard wondered whether the delay might be part of Microsoft's ongoing strategy to try to convince more users to move to the cloud, since Microsoft is continuing with its mission to roll out new featues for the cloud first.

And I myself -- like Windows IT Pro's Rod Trent -- wonder whether the decision to push back the next version of Windows Server might be connected in some way with the imminent end of support for Windows Server 2003. Maybe the Softies don't want to confuse the upgrade message and want to be able to tell those still running Windows Server 2003 -- for which all free Microsoft support, including security patches) ends this July -- that the platform to which they should move is Windows Server 2012 R2.

There's also the possibility that business users and IT pros have told the company that pushing out another major new Server release just two years after Windows Server 2012 R2 debuted might be too soon.

Microsoft officials declined to say why the company is delaying Windows Server Next. When I spoke to Mike Neil, General Manager of Windows Server at TechEd Barcelona in October, he told me the plan of record was to make the next public preview available in "early 2015," so something changed between then and now.

UPDATE: Microsoft officials provided this statement to explain the delay:

In order to build out these investments and take the time needed, we believe that allowing for adequate customer and partner feedback and participation is critical. Accordingly, we have decided to deliver a series of high-quality preview releases through this calendar year along with investments to accelerate at-scale customer deployments.

Interestingly, Microsoft is not delaying one piece of its System Center management suite. The next version of System Center Configuration Manager will be released alongside Windows 10, which is slated to launch in the fall of 2015, today's blog post confirmed. The blog post does not say the rest of System Center Next will be out this year; in fact, it makes it appear as though the rest of Microsoft's management suite also will be a 2016 deliverable.

Microsoft made the first, and so far only, public preview of Windows Server Next available on October 1, 2014 -- the same day Microsoft released the first preview bits for Windows 10. The next version of Windows Server includes new and updated Hyper-V, networking, directory services, Web application proxy and other features.