Personally I do not think that the new stuff is two seperate pieces, that is way too much thinking time for the designers at LEGO.
It is more likely to make new hair pieces that go under the hats. The problem lies in the fact that the point of contact between the pieces is not the same for every hair/hat LEGO has, so the piece would be limited to one or two uses only. To make a hat that fits over the hair would require a very big hat, and the connection would be suspect at best because there is no stud to connect to on top of the head.
I have this on my list of wants to, so I am all in, but the logistic of it are not as easy as they seem!