No, because of U.S. employment law. All people with a right to work in the U.S. (citizens, refugees, green card holders, etc.) have to be treated as equal and all people able to work in the U.S. on a visa have to be treated as equal so you can't have a rule that treats Canadians as different than Jamaicans (for example). Only visa vs. non-visa players, which is how MLS's international rule works. Players with a green card (Cummings, Koz, etc.) are treated like domestic players, players without one (Janniere, Smith, etc.) are treated like visa holders.