Competition chases easy money and high returns. With cheap oil, the 300's and 500's will come out of the desert by the hundreds if not thousands.
50 seat RJ's are probably just about free. 20 dollar oil makes a free airplane that burns a lot of gas competitive.
All the low cost guys are growing 8+ percent a year. While the majors are employing "capacity discipline". I wonder how this will turn out.....