There's another huge reason why Windows Mobile is struggling: the way MS competitors and OEMs boycott Microsoft, while Microsoft does not boycott them. Google has refused to port any of their apps to Windows Mobile, Apple does not port anything to anybody, while Microsoft has graciously provided powerful apps like the Office suite to both Android and IOS, plus beautiful ports of Bing and Cortana. OEM's boycott Microsoft because MS does not let them fill the OS with bloatware or skins, which is form the good of the consumer, but for the OEM reduces their differentiating factor in a viciously competitive industry.
If people could choose Google Maps, Google Play in their Windows Phone, if there was a Samsung Edge for Windows and if we closed a bit more the app gap, Windows Mobile will prosper. That's why i'll stick with Windows and see, because with the success of Windows 10 desktop/tablet OS, we will get more and more universal apps which will run on Windows phones without any additional effort. That is the best approach and strategically it has the best chances to win, because Windows desktops and tablets are not going away any time soon, and all new and updated apps will likely be Universal. And the Universal scheme MS has done is not the gimmicky crap seen in other platforms where the phone app is just pixel-augmented, instead MS UApps adapt and redesign beautifully and functionally to the device's form factor.
Eventually, even vicious competitors such as Google and Apple will have to buy into the UApp scheme to support Windows desktops, and in the process will also support Windows Mobile. The strategy takes time, but I'm sure it'll pay off, and much of the people jumping to other platforms will return to Windows.