As far as I know there are plenty of XNA games running on both pc and Xbox in C#. And that is pretty much the worst applications you can use c# for because, you know, latency. I don't see any real blocker to have complex c# apps on the desktop, apart maybe the quite shitty clickonce and the continuous need to have an upgraded .net framework to use the new features. But now for UWP apps the default is c#, they can be installed directly from the store, and with Roslyn you basically need only to target .net 4.5 to have all the features of the last version of the language. And this is a huge win that admittedly JavaScript already had because of transpiling. If I had to write a commercially distributed desktop application nowadays I would use for sure c# or f#, not JavaScript.