Not living there I cannot talk for the people of NC obviously but might offer an outside perspective.
I imagine if my area had a team which left, I'd be turned off the NBA for a while and concentrating on successfull college ball would give a solid area to put my basketball support into. If a new team started, at first it wouldn't be 'my team' for many people but as time goes by or success comes, even if it's just being competitive, then more and more fans will come back around.
If you stuck a team in a brand new location it might get alot of fleeting support while novel but then this would fade with lack of initial success. In a basketball hub like Charlotte where many fans have been put off the NBA, it will start slow but has the potential to be massive.
Much like we as fans from the beginning of the franchise have looked more at potential than immediate success I assume this is what the NBA is doing with Charlotte. For the same reasons we are liked for building gradually through young players and the draft then becoming great, rather than instantly being below average with vets and staying below average for years, so the support of the Bobcats will become great I believe and this looks like being the transition season for both our team and our support.
Does that make any sense? It's getting late here in the UK and I'm anxious for the game to start