Indigo partners has been on a mission to dominate the ULCC market. The Frontier executive culture is not in favor of many of Spirit's labor agreements.
I would expect with F9 holding a controlling interest, their will be some very difficult Union integration discussions particularly issues such as scheduling.

F9 management does not want a scheduling flexibility program like that at NK and I would not be surprised if they refuse to adopt such amongst both unions unless both unions come together strong and demand it is preserved.

As far as the upgrades and growth/movement potential, I don't know that it will have much benefit in the near term. It may take upwards of one to three years for a full integration and operational synergies to be established.

Going to be very interesting.