Surface Phone can rotate 360 degrees, new hinge APIs suggest
If there is a new Windows 10 build coming, then by looking inside it, you can see the new APIs added to the OS. APIs reveal what features Microsoft is planning dd to their future software and hardware releases.
Looking at an earlier version of Windows OS, namely Windows 10 Build 17704, there is an API that develops new ways for the operating system to respond to the state of the hinges of a dual screen device.