MS has indirectly paid my bills for the last 25+ years since I've been developing in the MS platform for that long.
I had WM 6+ before WP. I bought the Samsung WP when it first came out. Then I went to L900 and for the last 3 years I've had 3 L920s in our house.
Friday I got my two new shining L640. Why? Because they were only $40 on Black Friday. However, my son is getting an Android Moto X Pure for Christmas. That phone specs wise is very comparable to the L950xl. It is hundreds of dollars cheaper and has "no app gap". My son will continue to use the MS services he uses, but like the OP said, with much better functionality than the WM version developed by MS itself.
I've also owned an Xbox for over 13 years. Just two weeks ago I bought a PS4. Why, very simple. I?m into car racing games. A few years ago I bought a wheel for my Xbox 360. At the time the wheel was compatible with the Xbox 360, of course, the PC and the PS3. Then the Xbox One came out. Guess what, the wheel is not supported in the Xbox One. Now, a few racing games that I wanted are only available on the ?New Gen? consoles (both the Xbox One and the PS4.) For me to go with an Xbox one, I would not only have to buy the Xbox, but I would also have to buy a new wheel. My original wheel investment was over $500. Well, that old wheel that came out before the Xbox One or PS4 came to market, IS compatible with the PS4 but not the Xbox one. Why would I then buy an Xbox One so that on top of the machine expense itself, I would have to buy another wheel? Makes no sense. Of course in the Xbox case the number of people that are racing fans is not as large as the ones that don?t so buying an extra controller is not as huge as an expense as buying a new wheel setup. So the Xbox overall is doing okay (okay because for years it has been behind PS4 in sales.) But this just another example of MS letting its fans down.
Why am I talking about the Xbox/PS4 in this post?
As a 25+ years of developing for the Microsoft platform and being a ******. I now have purchased an Android phone for my son and a PS4. MS is pushing me away in some respects.
Will I still develop for the MS platform? Yes, I will. However, with Visual Studio I will also be developing Android and iOS applications for my clients? systems that I develop for them. There is no way my client will justify the development of a WM application when there is no market for it. It is possible that a Windows 10 desktop application might work for my clients and that case, yes it will be a Universal App just because it is there. But not because the clients would need it in WM10.
Bottom line, I think many people, after 5 years of failures with the MS mobile platform, are looking other ways to fulfill their needs.
People complain about Steve Ballmer and how Satya is doing so much better. Yes, maybe Satya is doing better for MS?s bottom line (which is of course important) but this post is not about MS?s bottom line. It is about WM. When it comes to that. Steve, after making the huge mistake of not staying on top of the WM environment, try to rectify it by buying Nokia so MS could have its own mobile division. Then came Satya. He fired 18000 people. He stopped all development of all flagship Lumia phones. And he directed the teams to develop better mobile applications for other platforms instead of his own. To me, Satya is not doing better for the WP/WM landscape. He?s actually pushed many people to other platforms as the OP said. There is no MS service (with exception of Cortana and that is coming) that he can?t get from his new Android. And the same is true with iOS.