I do not believe that shoulder position at impact has changed for pros in the last 100 years or more as far as being 'more open'. I think that if you measured a pro at setup using the rotation around the spine you would find that the pro is open by a lot.
To illustrate my thinking I have provided a pic of the Model Pro at setup. I have drawn lines to try to indicate the rotation of the shoulders relative to the spine. It looks like the shoulders are open by 20 or 30 degrees maybe more if measured on the basis of rotation around the spine? Please note that there is a problem with perspective from this camera angle which I think would tend to make the angle look more acute then it actually is.