a new Windows version with no direct upgrade path and breaking backward compatibility with Win32 ? Good luck getting devs and enterprise IT on it.

Project Centennial is an amazing piece of virtualization but it has its caveats (https://docs.microsoft.com/en-us/windows/uwp/porting/desktop...): it won't be able to convert every legacy software (why isn't Office on the Windows Store for example ?).

At best, it will target locked down hardware like consoles and tablets, but isn't what Windows S was created for ?