We can use redirectors to map values of properties that don’t exist anymore to another property of same type, or just redirect in case the property name have changed.
But for latest Unreal Engine releases, there’s a problem in this since they changed UProperty types to FProperty.
I am working to fix it:
In terms of binary file compatibility, the system is built to not crash when you change the binary size of a class so old save files will always be supported even if the sizeOf(class) have changed.