for the panthers, it goes both ways. a successful redevelopment of the parking area will increase foot traffic and residences near and BB&T. this could lead to increased attendance of games because there will be more restaurants, bars, transportation, etc around the arena.
on the other hand, it will also reduce their negotiating leverage next renewal since the resulting hotels, commercial spaces, residences would produce more in taxes than the bb&t by itself (this has yet to be proven, and is part of what a 10 or 20 year master plan would tell you). this is precisely why the county insisted on obtaining the rights to develop the parking lot. expect the subsidies the county gave to viola et. al. to disappear after 2028. without those subsidies, if the team is still floundering with respect to ticket sales, etc, there will be far less incentive for the county tax payers to bail them out a second time. this could result in the ownership moving the team in 2028-29.
hell, i wouldn't be surprised if the study also detailed three scenarios at the end of the 10-year master plan: (a) panthers renew in 2028 at market rate (b) panthers leave or (c) panthers renew in 2028 with similar subsidies.