I keep hearing the A380 supporters arguing that it improves efficiency at slot-restricted airports. But this may not be so. Due to wake turbulence, aircraft following a Super must generally maintain larger distance separations than when following Heavies. Further, gate and taxiway limitations may also increase Super handling costs and thus reduce airport efficiencies.
The wake turbulence argument is a marginal one given the large reduction in the number of 747s in service so, on a one for one basis, the actual distance required for a greater number of A380s would not impact as much on slots as the 747 did when it was introduced. The argument could easily have been used for the arrival of the smaller wide bodies and anything else replacing the 707/DC8 fleets and wake turbulence didn't really trouble LHR and other European airport slots, when BA replaced its Tridents with 757s which required greater separations.
As far as gate and taxiway limitations are concerned, this exercised both Airbus and airport managements over 20 years ago. Whilst fillets are required for many taxiway turnouts, the gate imprint of an A380 was deliberately constrained to the space required by the 747-400, something the 77X cannot offer without the extra costs and maintenance of folding wingtips.
As for jetways, turn round costs etc., it is interesting that airports such as Auckland for instance, which is not slot constrained, which every day handles 3 x A380s at once at a moderate sized terminal, campaigned hard to get its A380 services for the increase in passenger throughput with no increase in movements or environmental impact.
Slot constraints without the availability of super sized aircraft reduce income for airlines and airports are a recipe for a static or even a declining industry and that goes against all the predictions of the growth the industry expects.