Looks like A380 with the max seating capacity of 853 would be significantly cheaper to operate per seat than anything out there. The current installed maximum is 615, hinting that the market is not quite there yet.
I could imagine that some airfields would soon increase their per plane landing prices as a result of crowding. That could make the A380 more profitable.
It's the 4 engines which gives airlines A380/747 fuel cost problems. Both fulfil relatively niche markets and are gradually being displaced by the more-efficient and flexible twin-engine A350/787 types. We're just starting to see the secondary market for A380s now which is a good indicator for its long term commercial viability.
Twins are actually overpowered compared to comparably-sized quads due to engine-out climb requirements. In terms of raw seat-km-litre they are therefore slightly less efficient.
A good example is the old A340-300 quad, often maligned for being underpowered. Now that it is mostly retired data has emerged that it was more efficient than the rival 777-200 twin.
Where twins are cheaper is in terms of capital costs and consumables, though ETOPs requirements mean you need more technicians to service a twin ( separate teams for each engine ).
I would've thought that more passengers on the same number of planes would be profitable for airports, considering how they double as shopping malls these days.
Air traffic control is difficult and gets more difficult with more planes in the pipeline. At very least we can safely assume that reputation of unsafe airfield is very unprofitable.
Indeed, but you'd think that would make airports encourage high-capacity planes - fewer planes for the same number of passengers means less pressure on air traffic control.
Airlines are pushing for more premium classes and less economy seats. 853 is all cattle class. The configuration of the A380 I flew with (LH/BA) has lots of cabin space reserved for Premium Economy, Business and First. I believe it’ll only grow more pronounced as the established carriers are fending off low cost airlines.
I could imagine that some airfields would soon increase their per plane landing prices as a result of crowding. That could make the A380 more profitable.