In the next five to ten years? Nothing. More of the same.

SWA doesn't want to assimilate another aircraft type. They liked the A220, but Boeing made a counter offer. Bringing on a new type, when they don't have to, is cost prohibitive.

SWA won't buy anyone that's not in bankruptcy. Yes, they bought FL, but what did they really gain? It cost a LOT of money and goodwill. Changed the corporate culture, continuing with neither. It's no where near the condition it once was. SWA made out like a bandit with the non-merger, purchase of TZ. NK doesn't offer WN anything they can't do themselves.

USGubmint may not allow another merger of size due to anti-trust measures unless one carrier is in jeopardy of shutting down. This may be the ultimate determination for the industry going forward. I think all airline management knows this. AS and HA could, possibly happen, or maybe something similar.