That building is set to make way for an expanded mall / lawn area in the longer range IMP. The School of Social Work would need to be relocated first which I suspect may end up in the buildings vacated by the existing Pardee School who are spread out among Bay State Rd buildings.
It's being placed in a spot which is currently surface parking, not a brownstone:
"Project Description
Trustees of Boston University (the “Proponent”) proposes to transform an existing 56,900-square foot (“sf”) surface parking lot into the Fredrick S. Pardee School of Global Studies (the “Pardee School”), a 70,000 sf gross floor area (”GFA”), 186-foot (“ft”) tall academic building with approximately 50,800 sf of open space (the “Project”) at 250 Bay State Road on the Boston University (“BU” or the “University”) Charles River Campus (the “Project Site”)."