I said in my first response that it has declined in popularity. Everything has from the days when people had 4 channels on tv and no internet.In this thread @UTFO made the comparison between craft beer and the 500, and now you're doing it with the NBA? Not sure about either comparison.
Just for humor:
http://www.theonion.com/americanvoices/on-indy-500s-declining-popularity-17552
But it is ignorant to say it only matters in central IN. It is still the biggest event for racing fans/drivers worldwide.