I don't think Delta would be wise to delay its next decision on replacement of their B767 aircraft (either the 300's or the 400's) for Boeing to find their niche and move ahead with the MOM (middle of the market) twin isle plane (B797?) with 2 versions to directly replace the very old B767's. Airbus doesn't seem to have something within the seat range and / or mile range to fill this window either. At this moment, the A330-800neo (which Delta has none of) is about the closest to be the replacement. A339 (A330-900neo) is "almost" too large for a direct one-to-one replacement. If this is what Delta is working on for future changes, some of the current daily Trans Atlantic (TATL) routes will probably be cut back to between 3 and 5 times a week - which makes since. They will eventually go back to daily. This happened to DTW-NGO post covid. 4 times a week, then twice a week, finally the disappearance of this route all together. This route was abandoned probably for reasons other than aircraft size, more likely profitability.