Thanks to a number of sources, here's what we understand will happen with Windows over the next 15 months. In April, Microsoft plans to release Windows 8.1 Update 1 (or GDR1 internally) and Windows Phone 8.1. After that, Windows may likely not see another major update until April 2015, the "Threshold" release. We previously pegged this as Windows 8.2, but now there are reports that this release will be labeled Windows 9 instead due to Microsoft wanting to distance the platform from the Windows 8 "debacle."
According to Paul Thurrott's Supersite for Windows, Microsoft will talk about what the company plans for Windows 9 this April during the Build 2014 conference. We will reportedly hear about Microsoft returning the Start Menu back to the desktop, and the ability to run Modern UI-style apps in Windows. Microsoft wants customers to get excited about the platform, and these two details should help.
Thurrott also lays out a roadmap for developers, reporting that BUILD will not produce early bits of "Threshold," as the Redmond company won't even begin development until later that month. Currently, Microsoft is "firming up" the features it plans to release in the Windows 8.1 Release 1 (or Windows 8.2; it could be either).
"Maturing and fixing the 'Metro' design language used by Windows will be a major focus area of Threshold. It's not clear what changes are coming, but it's safe to assume that a windowed mode that works on the desktop is part of that," Thurrott writes.
The report states that Microsoft will likely make three milestone releases of "Threshold" before its final release. Thurrott speculates these will be named Beta or Release Candidate, but questions whether they will or will not reach public hands. If Microsoft is indeed trying to shove Windows 8 in a closet, getting a public beta out with cool features may be on the Microsoft cards, similar to what it did with Windows 8.1.
Thurrott reports that fixing the Modern UI (Metro) design language will be a major focus in Windows 9 "Threshold." So far the extent is unknown, but as previously stated, Microsoft is expected to bring Windowed modes to Modern UI apps.
Windows Phone 9 is also expected to be part of the "Threshold" release in April 2015, bringing both platforms closer together. By then, Windows Phone 9 and Windows RT are expected to be one platform. Also expected is a unified storefront bringing Windows 9 and Windows Phone 9 together.