I would definitely say that 3 hubs is not a bad idea. For example, a major airline like Continental Airlines has 3 hubs, Newark, Houston, and Cleveland. Of course airlines also have smaller hubs and focus cities but let's not get ahead of ourselves. I will say though that in reality, the large airlines do normally dominate the smaller ones, but you certainly don't see American carriers flying domestic Austrailian routes for example. If there is going to be a hub limit expansion, it should only be in the home country of the airline. I recognize this could create an imbalance in certain areas so it would have to be tinkered with.