Microsoft has remained mum on the specifics but it seems like the Centennial App Converter will simply wrap around the existing program and offer the clean install and uninstall of UWP. The Centennial App Converter sounds sort of like the App-V app virtualization offered to enterprise customers. The app remains unbound by the UWP sandbox and is free of the restrictions imposed on native UWP apps.
All of that makes it seem like UWP doesn’t have to be as restrictive as it currently is. Perhaps, the best way forward for game developers is to create a normal Win32 game then package it in the UWP using the Centennial App Converter. This allows both the flexibility and power of traditional Win32 applications while providing a more unified and simpler platform through the Microsoft Store.
By converting existing apps easily with the Centennial App Converter, Microsoft is hoping to address the biggest concern with their UWP store, the lack of applications. By moving current Windows applications to UWP, the Windows system will also become more integrated and unified. There is no word yet when the App Converter will actually launch but expect it soon.