Or the Reds?
No, you're definitely right and every point you make is a good one... however, the voracious nature in which the American public inhales anything "FOOTBALL" really makes me think they'd have a legitimate shot to make it work if they controlled costs, league size, and played in appropriate venues. Additionally, I think your idea of targeting cities where there isn't otherwise a significant professional football presence would be smart. (Louisville?)
Also, you can bet your bottom dollar that Cuban will put into HIS league everything that NFL fans dislike the most about theirs. (without becoming a sideshow a la the XFL)