I would be surprised if it was in front of Starbucks, since the fireworks is usually only a few minutes after the parade and Main Street doesn't provide the best views of HS. Last year IIRC, they had reserved seating at the area around the Partners statue (not sure if this is called the hub?) off to the right side facing the castle. Not sure if it will be in the same area this year or not, but I would be surprised if it was anywhere on Main Street.
Then again, I haven't been following the updates on the BB event so I could be completely wrong!