This is how much of the foss world desktop solutions looks these days, with Python for non-performance dependant 'glue' code which calls high performant C/C++ code where needed. I fail to see what there is to gain by exchanging Python with C# for the non-performant code?
Anyway, native code is here to stay and so is managed code. On the end user desktop managed code has failed to make an impact, likely due to end users preferring native code alternatives where available due to the increased resource usage of managed code applications. Meanwhile managed code solutions like Java and C# are strong on in the enterprise sector where ease and speed of development trumps pretty much all other aspects. Then we have new languages coming out like Go, which offers native code but with automatic garbage collecting and built-in language properties for concurrent programming which may find presence on the desktop once it matures (or atleast reaches version 1).
As always, code talks, bullshit walks. The success or failures of the respective language solutions out there depends entirely on code being written in them and how/if that code is recieved and utilized, and my opinions just like anyone else's are just that, opinions.