Well, it certainly looks now like it will in fact just clear the height of the Pru, as expected
I've always felt that, while impressive, the Boston skyline has appeared oddly proportioned because its two (now three) tallest buildings are outside the Financial District core and also often appearing to stand alone and apart from one another with few buildings as tall in the immediate area of Back Bay and Copley Square. Since we're obviously limited in height by Logan for much of the city center, I can only hope for a handful of proposals in the future of a certain height to both link Back Bay with the core and also envelope these tallest buildings a bit more so they don't appear to rise from so little.
That being said, this building certainly helps that along tremendously, and the Winthrop Square project will boost up the other end as well.