Honestly, as someone who had Uber-hubs before, large aircraft for longhaul are a waste of time and money.
The biggest aircraft which are viable on longhaul are in the 250-300 seat range. More than this is overkill. During the last stint from 1979-1995, I had 10 742s in total in my fleet of over 4000 aircraft. In my longhaul fleet, I had about 500 733ERs and 735ERs for routes from western Europe - eastern North America and Africa and eastern Europe - Africa, Middle East and India , which were supported by 20 752s and 150 A320s. I also had over 200 763ERs for pretty much the rest of the world. To repeat 747s are a waste of money. DC8s, DC10s and L1011s are really the largest planes you should buy in any real numbers.