It’s the end of an era for Windows on smartphones. Today is the final day Microsoft will officially support Windows Phone 8.1, which was made generally available to consumers on July 15, 2014. The end of the OS also signals what most people have accepted for several years. There are only two mobile operating systems now — Android and iOS. Some of you might be saying, “What about Windows 10 Mobile?” What about Windows 10 Mobile? Microsoft’s mobile OS is only available on just over 20 percent of all Windows smartphones, as shown in a recent report from AdDuplex . That means that nearly 80 percent of all currently active Windows smartphones will be running on unsupported operating systems after today. That also means that many Windows Phone 8.1 owners have chosen not to update their devices to Windows 10 Mobile, if they are indeed eligible to receive that update. Even more telling is the fact that Windows 10 Mobile has not received much in the way of new features since...