The update was originally scheduled to arrive towards the end of this year, but Microsoft reportedly decided to postpone the arrival of the second major set of new features for Windows 10 to coincide with the next wave of Windows 10 hardware launches. This includes new PCs, tablets and possibly even Surface Phones from Microsoft's Devices Group.
As I noted recently, Microsoft's Windows and Devices Groups are working increasingly closely -- not a surprise given both teams are now under Executive Vice President Terry Myerson. My sources have said Microsoft is prioritizing and tailoring new features coming in Windows 10 largely based on what the Devices group wants and needs to showcase its hardware.