F9 guy here...
Both Airlines have bottom of the barrel contracts. The good thing is that both are much closer to industry standard then few years back. So hopefully next round of negotiations both will be industry standard.
F9 still has a ways to go when it comes to improving its operation. If we do go public that will improve drastically because board of directors will not put up with the current practices. We are scheduled to have 215 airplanes by 2024 (I think we are around high 80s now). Indigo is not a high risk investors, so i don't see them moving airplanes around. Only thing that worries me is selling those frames to a higher bidder. Upgrades are running around 55-57%. That was the case for me when i upgraded and still is today. There is a strong rumor of a TX base possible this year (aus or Sat).
NK has great crews, they have been nothing but accommodating whenever i ride on them. I actually prefer to ride on them over most airlines.