I may of course be wrong here, but I think that promotion and relegation only works in countries where football is the number one spectator sport. FIFA may make special cases for countries (=markets) where there is chance to expand football's presence commercially, but in general any significant growth of football would not suddenly topple other (top) sports commercially in any given country and tap into their funding. And promotion / relegation requires more clubs to have decent money than in a franchise model.
Examples to the contrary are welcome!