do you know what economies of scale actually means??
the 380 can hold up to 850 passengers, the 787 can hold 250. if your figures are correct, the boeing will be over 4 times more fuel efficient than the airbus.
it may be able to do x number of trips to new york than the airbus, but an airbus can carry over three times the number of passengers. so it only needs to go once.
saves time, saves flight crew saves landing fees and most importantly, instead of doing the extra trips from lon to new york the airbus can be off somewhere else earning its money - makes no sence at all