You are worried about delta buying 100 Airbus to replace their old fleet, and you aren't worried about frontier buying 200 Airbus to grow their fleet?
You guys really think Southwest will be the launch customer for the next Boeing model? I might take that bet. I think it's too high risk and too expensive to integrate. The 737Max10 looks right up your alley. And then after that, the 737Max10LRGT500XXL might work nicely.
In all seriousness, I see no need for you to be concerned. The loyalty of your customers is priceless