I wonder if Delta is planning to upgauge their TATL fleet? 787 is an okay 767 replacement for the current market, but maybe not the best choice if demand increases in the next 20 years. They can use the A350-1000 to markets that are currently served by multiple 767/A330 flights per day, and redistribute the 332s and 764s where they use 763s today.

When was the last time Delta purchased a widebody from Boeing? I think they are already Airbus captive in terms of acquisition.