I haven't even been inside the building but by looking at pictures, the cost to transform that building into what they'd like is an engineering nightmare. The NBA likely wouldn't allow it because it probably would risk losing seats for a period of time while the building gets reworked. We are talking adding a new concourse, demo the existing section and then installation of a new section. In phases that would take 3 to 5 years minimum with interruptions. The venue likely wouldn't be able to have concerts in the off seasons because of construction.
This is just from my experience with construction projects and every site is different but that is what I am seeing would likely happen.