Like every airline, SWA is maturing. With that comes higher costs. SWA's pilot costs alone are higher than anyone else out there. Yes, their efficiency is awesome, but 95% of airlines have copied it.
SWA is going to have to find a way to spread these costs out. The best way to do this is to go international, and go after the Legacy carriers. They do this and three if not four of us our out of business. We ran for the woods when they did it domestically after 9-11. If they start in LA etc and then move to Europe, the Legacy carrier could not compete with them.
Problem is that WN has such an awesome balance sheet that they would just start to feel a little financial pressure when the rest of us would be on the floor. They have the money to kill any other carrier they want to. It will effect their bottom line to do this, but they can if they so choose.
I see them growing in the leisure markets South of the USA in the next three to five years.