And the game-industry as a whole is moving to data-oriented design, which tends to be hard to do at best (if not downright impossible) in most GC'd languages.
Regardless the transition from C to C++ has no performance cost (often a performance advatnage), so I'm not sure why you're bringing that up as some significant migration in this case? It doesn't support any argument for a transition from C++ to C# or similar, as that comes with a huge performance cost. Particularly in an era where CPU performance hasn't improved for almost a decade now.
Additionally dataflow languages are better suited for GPGPU programming than plain old C and C++, as Google is exploring with XLA on Tensorflow, and game engines with graphical tooling for shader generation.
Again, lets come back in 10 years and see who was actually right.
Eventually game devs migrated to proper C.
A couple of years later, C++ code in game engines, was not even "C with Classes", rather C compiled with C++ compiler.
Eventually game devs migrated to proper C++.
Looking at the past, which I was partially part of, I see HPC# as a stepping stone into regular C#, in a similar vein that C code of yore was full of inline Assembly.
It is of course a matter of opinion, however I like to look at the past to see where the future leads to.
So lets see who's is right in about 10 years, regarding how game engines get implemented.