extern(C++) infer linkage from interface?

[bitwise via Digitalmars-d]

I have a class with callbacks that can be overridden, which are inherited  
 from an extern(C++) interface. The callbacks are called from C++ code. Is  
there any chance that the linkage will be inferred in the future?

To be clear, couldn't the extern(C++) just be inferred in the class  
'MyTest' below?

extern(C++) {
     interface Test {
         void Foo();
     }

     void register(Test test);
     void unregister(Test test);
}

class MyTest : Test {
     extern(C++) {     // seemingly unnecessary boilerplate
         void Foo() {
             writeln("foo");
         }
     }
}

void main() {
     MyTest test = new MyTest();
     register(test);
     while(...) {}
     unregister(test);
}