Aside from the arena size I don't think the NBA is particularly interested in the area. They have philly and dc which already cover a majority of the viewership they would get from a baltimore team. With a baltimore team they would get more viewership but I imagine it wouldn't be massive as any basketball fans south of Glen Burnie are likely already wizards fans and any north of bel air can easily watch 76ers games. So baltimore would really have to push to get the NBAs attention and they would have to either move a team or add expansion teams and I don't think either of those are likely to happen in the near future.