Relegation/promotion would be fascinating. You could even have it across multiple tiers (IA>IAA>II>III). It would create great drama (not to mention ratings) as struggling big-time programs with coaches on the hot seat try to avoid relegation, and also spur interest/ratings at the IAA level as schools fight for promotion. How big a story would it be if the likes of UMass, Montana, App State etc. get a chance to play a season with the big boys and knock off Michigan or whoever in a game that counts. I suppose the networks would have to become comfortable with the idea of constantly changing inventory (they probably don't worry about things like metro TV viewing areas in England and Spain) and of course big schools aren't thrilled with going to tiny stadiums (hey ManU didn't mind playing at Burnley) but it would be fun.