Just so you guys know, I created those addresses for the thread as a general idea when the Schuylkill Yards plans were just released.
It seems like Brandywine is using the initial plans and renderings as guidelines to what they're doing, but it seems like they're tweaking things here and there as demand dictates.
With that said, it looks like that actually ADDED a few floors to a planned building, not decreased floor count.
If you look at initial renderings, there was this photo:
This shows a ~10 story building fronting Market Street where the current bank pad is, and where the address of this proposed building 3151 Market would sit. You can see the future potential "supertall" to the right of this, and the Drexel Paul Peck Center building in the foreground in the bottom right of this image.
Then, there's a highrise directly behind this that sits on JFK Blvd, where a portion of the current drexel lowrise building sits. I labeled this whole site as "3151 Market," but it's possible Brandywine is treating these as two separate sites and buildings with two different addresses? I could be wrong, but I hope that makes sense and I'm not rambling too much.