There's a new world's longest flight -- with a catch
https://edition.cnn.com/travel/article/air-transat-a321-longest-flight/index.html
I think that there will be little difference between dual-aisle aircraft and single-aisle aircraft about comfort during flight except for first class users.
The problem will be frequency of fueling. Airline companies will have to revise timetable to ensure time for fuel.
