I don't see it happening either. AirTran was bought on the cheap. They were losing money and fuel was through the roof. Look at airline stock performance and price today vs then. The only thing I could see would be a fringe player like Sun Country or a minority stake in a foreign carrier.
When you think about an acquisition, think about it in the lens of an accountant, not a pilot. What do you get for the $$$?
We got a lot from AirTran and knocked out a direct competitor for cheap.