The toolkit is not part of Apple platform apparently. It is a development tool that can be used to evaluate porting no more no less. I see no changes in the platform itself.
Including things in the platform is a double-edged sword; the platform has different compatibility policy from windows, and old games typically do not get updated with mandated platform changes (such as a requirement for 64-bit).
Swift developer were upset by concurrency because the language’s deep integration with the platform meant the best features were (for a while) only accessible for apps targeting the latest platform versions exclusively.
They built Game Porting Toolkit.