My reasoning, extremely amateurish I realise, is this: JetBlue is the fifth largest airline in the U.S. (of the majors), I'm not sure how easy regulators would sanction a merger between JetBlue and a legacy/SWA. New York is a huge market, but one where JetBlue has a significant presence. Plus, JetBlue doesn't offer anything the legacies don't already have. But, they are innovative in their thought process, haven't acquired anyone, but have shown a tendency to "team up" with other airlines. A merger with Frontier offers an established and more respected brand name than Spirit, a somewhat loyal customer base (which JetBlue relies on) and aircraft (Airbus) orders. A merger with Frontier offers middle America access, something JetBlue doesn't have a lot of.

The talk of a contract extension does worry a bit here at Spirit....