System programming != Low level programming.
The day someone writes a C++ compiler, as optimised as the present ones, 'in C#'; that day I will say 'welcome new C++'.
Why would anyone want to create unmanaged C#? It will give the world another C++. Believe me, we won't switch from C++ in case of Game Engines any time soon.
Focus on creating games and use C# if you like.