Should Atlantic and South America travel rebound to "normal" they would not have adequate widebody fleet to cover and they don't have much left on the order books (1 more A330 left to deliver and that is it) . Remember they just retired the smaller 777 fleet (18 frames) that was younger and outside of 2 or 3 777-200LR routes their newer A350 and A330 could handle pretty much all of the 777-200ER routes more efficiently.
The 767 fleet (767-300ER and 767-400ER) is showing as 72 frames with 31 of those in storage, thinking some of those 31 are going to Amazon. During normal times in peak trans-Atlantic summer DL would typically have 8 to 10 of those rotating in/out of maintenance or refurbishment with the rest plying the 8-12 hour international runs (Europe and South America), then winter slowdown to Europe they throw the slack widebody aircraft to sun and sand routes (Florida, Arizona, Mexico, etc.) to get people down south from the snow and cold. Sun and sand routes would be fine without widebodies as they don't need the range, majority of trans-Atlantic outside of NYC/BOS need the range of the widebodies.
Long story short the 767 replacement is going to take some time, they pretty much just finished an extensive years long refurbishment on them that makes them look pretty much new (same with the 757, A319, A320 fleet) which are all the oldest birds in the fleet.
