Microsoft has been working on Windows 10's next set of major features and improvements for a while, but this is not a secret. Members of the Windows Insider program already received quite a few pre-release builds and, according to WinBeta, the first Redstone update will go live in June. Inside sources claim this update will focus on the convergence of different Windows 10 devices while the second such update has been pushed to 2017.
The reason for delaying Redstone 2 is that quite a few next-gen Windows 10 devices will also launch in the first part of 2017, so pushing back the update to match their unveiling sounds like a logical move. WinBeta also reveals that "Updates to the Start Menu and Settings app are in the works, as well as an improved Action/Notification Center that will give users much more control over their notifications." They also mentioned that the Control Panel will continue to fade, more legacy elements being expected to become parts of the updated Settings app.
Since the BUILD conference is now less than a month away, we will hear more about Windows 10 Redstone then. The preview build of the first Redstone update is expected to show up at the event packing extension support for Microsoft Edge, but the feature is not expected to go public before June.