JetBlue is a small rival (JetBlue at ~5% of US traffic, Spirit at ~3%) to the big 4 United/American/Southwest/Delta (each with ~17%). At least on the surface, a larger JetBlue might be more competitive rather than forcing them into the unequal partnerships like they have with United at the moment. Certainly, some jobs would be lost, but I do think that Spirit dying is a worse outcome than joining another small airline.