Why not just invite the top teams in the country and do away with "regionals"? You could still have a National tournament but this way you'd make sure you get the best teams there - not just the best from each "region". I guess you wouldn't get regional tournament fees this way.
What's the point of having a USA Hockey national tournament when some teams are full of players who are not American?
Get used to it. Rules are constantly being relaxed to allow players move across previous boundaries. Junior leagues allow more imports than every. NCAA is now somehting like 35% non US players and growing.