Windows is on more than 90% of PCs (including a lot of Macs), Visual Studio is one of the most popular development environments, and C# is one of the most sought-after skills in the job market. And as others have noted, Xamarin for Visual Studio lets you develop for iOS and Android as well.
https://xamarin.com/visual-studio
Also, C# isn't compulsory because you can develop in HTML5 instead.
So, it might be impossible to get people who specialize in iOS apps to develop for WP8, but it should be possible to grow a comparable ecosystem. And making apps run on both W8 and WP8 would be a good move in that direction.
The short term view may be bleak but the future is uncertain, and the long term _could_ look different.
Also, C# isn't compulsory because you can develop in HTML5 instead.
So, it might be impossible to get people who specialize in iOS apps to develop for WP8, but it should be possible to grow a comparable ecosystem. And making apps run on both W8 and WP8 would be a good move in that direction.
The short term view may be bleak but the future is uncertain, and the long term _could_ look different.