Everyone who tracks Windows 10 development probably knows that the next major operating system update is codenamed Redstone and it will come in two stages, exactly like we got Windows 10 RTM code name Threshold. Build 10240 is the Threshold 1 release and build 10586 is Threshold 2. New information about the next Redstone update indicates that RS1 will be in 2016 and RS2 in 2017.
Previously it was rumored that Windows 10 Redstone 1 will come out in June 2016, and the second wave, Redstone 2, was expected to be released in October 2016. However, new information about release dates has leaked that states Microsoft has postponed Redstone 2 to Spring 2017.
The information comes from WinBeta, which is a well known source for various insider info related to Microsoft.
According to WinBeta, the first wave of the Redstone update (RS1) which is currently available for Windows Insider program participants, will focus mostly on the convergence of different Windows 10 devices such as PC, Xbox and Phone. RS1 will heavily concentrate on the Universal App Platform, bringing the Windows Store to Xbox One and introducing more Project Centennial and Islandwood apps to the Store.
Currently released builds feature very minor visible changes to Windows 10 like the offline scan feature in Windows Defender or taskbar properties inside the Settings app.
As for the branding of the RS1 update, it is likely, but not definite, that Microsoft will opt to use the same naming scheme they used for Windows 10 Threshold 2 update which became "Windows 10 Version 1511" since it was released in November 2015. So RS1 should become "Windows 10 version 1606", i.e. June 2016.
The Redstone 2 update will get a bigger focus on first-party apps and will expand the user's task flow across multiple devices. The most interesting feature of the Redstone 2 update is Task Continuation which will allow users to start a task on one device and then resume and finish it on another. Also, Redstone is expected to bring notable changes to Action Center, Microsoft Edge, Cortana and may also add some integration with Office 365 services. Cortana is expected to become a system-wide assistant. Notification Center / Action Center might get support for widgets, offering quick snapshots of data, synced across your Windows 10 devices. Microsoft Edge will get extensions support: this was confirmed in Windows 10 build 11082, which already has this feature partially implemented.
Continuum will also be a notable part of the Redstone update. Continuum in current builds of Windows 10 is a user interface which scales across devices. It is likely to evolve to incorporate completion of tasks across devices. SMS texting and cellular calls will come to the desktop via Continuum from a Windows 10 Mobile device. This will allow you to make calls directly from the PC, as is already possible with Mac OS X and iOS on Apple devices.