MCO would make a lot of sense. DL has ATL and AA has MIA. UA doesn’t have any SE hub. Terminal C has space to launch WBs and Spirit is talking about “right sizing” the airline so who knows if they reduce their footprint there.

I know there’s market for MCO to Europe and South America. DL currently runs Orlando to Amsterdam, British to Gatwick, and Virgin to Heathrow. All with solid loads. I believe that UA can be a force to be reckoned with if they decided to do a hub out of MCO.