I think this is actually a pretty good suggestion.
Obviously there would have to be a cap in the number, so that one dominating team wouldn't become ridiculously dominating. A not very high one.
On the other hand, it would definitely hurt close leagues teams, as it would make it easier for dominating teams in smaller leagues to get big crowds and consequently more money.
On another hand (yup, a third hand), the way it works right now already allows this, so it shouldn't represent great change in that aspect.