The number of rumors and patents that have shown up for Dual-Screen Phone is pointing to the fact that in 2018, we will see a lot of OEM coming up with Dual-Screen Mobile devices. Looks like Microsoft will be betting big on this form factor, especially with Windows 10 on ARM, and Snapdragon Processor delivering long battery life.
In a patent application, cited by TheWinCentral, Microsoft has explained their perspective about why Dual Screen folding phones are about to surface dominantly in the market. The patent application, from Microsoft, explains:
 Modern mobile phones and tablets have evolved over recent years to the point where they now possess a broad range of capabilities. They are not only capable of placing and receiving mobile phone calls, multimedia messaging (MMS), and sending and receiving email, but they can also access the Internet, are GPS-enabled, possess considerable processing power and large amounts of memory, and are equipped with high-resolution color liquid crystal displays capable of detecting touch input. As such, today’s mobile phones are general purpose computing and telecommunication devices capable of running a multitude of applications. For example, modern mobile phones can run web browsers, navigation systems, media players and gaming applications.  Along with these enhanced capabilities has come a demand for larger displays to provide a richer user experience. Mobile phone displays have increased in size to the point where they can now consume almost the entire viewing surface of a phone. To increase the size of displays any further would require an increase in the size of the phones themselves. This is not desirable, as users want their mobile phone to fit comfortably in their hand or in a shirt or pants pocket.  As a result, dual-display devices are becoming more popular. With a dual-display device, the mobile phone or tablet can include an open, expanded position where both displays are flush so that the user feels like there is a single integrated display. In a closed, condensed position, both displays are face-to-face so as to protect the displays. In a fully-open position, the dual displays can sit back-to-back so the user needs to flip the device to view the opposing display.
Microsoft also points that dual-display mobiles already have a problem, and its the hinge. The devices are now thinner and hinge-connected with them will protrude out. The hinges will also have to evolve to make sure they go inline with the thin devices.
 Hinges for such dual-display devices are problematic. Typically, the hinges can protrude from the device as it switches between positions. As devices continually become thinner, hinges need to be adapted to accommodate the thinner displays without further protrusion from the back of the device as it is opened and closed. Additionally, excess slack can make the two displays feel loosely connected. Other problems include that the displays do not open and close smoothly. Still yet another problem is the ability to stop the displays in any position as the displays are opened and closed. Torque or friction hinges are known and offer resistance to a pivoting motion. However, the friction hinges can be bulky and protrude from the device.  Therefore, it is desirable to provide improved hinges for multiple display devices.
That said, Microsoft is working on a solution which answers this problem. Using this solution, both the display will be able to rotate around each other in 360 degrees with respect to each other.
It will have at least one flexible connection member The hinge mechanism has at least one flexible connection member that follows a generally S-shaped path when the displays are in a tablet position. In some embodiments, a second flexible connection member can be added that follows a mirrored S-shaped path. The S-shaped path of the first flexible connection member and the mirrored S-shape path of the second flexible connection member together create a cross-configuration.