The following is my opinion.

The gulf carriers will own the southeast asia/Africa traffic, that is a given due to their advantages. But barring rules changes here that will be it for U.S. traffic.

But with the gulf carriers it is all about geography. Geography has given them an advantage in connecting passengers to certain points.

But geography has also placed them in a very dangerous political spot. Saudi Arabia is in trouble. The problems in Yemen will not be contained and the jihadists are now striking in Saudi Arabia. IS now claims two states within Saudi Arabia. If Saudi Arabia has an arab spring event the gulf states are toast along with their mega hubs.