Delta has projected lower passenger volume for a long time after the pandemic is over. Emirates has even stated the days of the A380 have been shattered, so it makes economic sense to get rid of the larger platforms. The 767 fits in with an A350 - A330 - B767 size structure by passenger volume per plane if Delta's projections say they can no longer fill a 777. I'm not current on Delta's plan for retiring the 767. I remember them stating they would be interested in being a launch customer of a Boeing NMA, but that was a few years ago and their current plan appears to get rid of anything without a side stick. Will they become an A321-XLR customer using that to fill the gap when they eliminate the 767 and 737-900ERs?