I've said it before, and I will say it again. The advantage for the A380 is cost structure. The resources in aviation that are either increasingly expensive (where they are marketed) or in short supply (where they are regulated) are overwhelmingly the ones that vary with aircraft movements, not load. These are the semi-variable costs in econospeak.
You don't need more slots or more air traffic capacity to load more pax - you need them if you are going to put on another flight. Where strict noise restrictions exist, this limits the number of movements, not the load. (I wonder how long it will be before permission to move out of hours is marketised? Say you are QC8 and need to dispatch late at night from LHR. Wouldn't it be a nice little earner for the CAA if, instead of quotas, they sold the permit? So - does it cost more to pay for the go or to put up the pax for the night?) Even fuel varies less with load than with per-movement factors (specific consumption, wind, range, alternates). Can anyone really see Leeds Bradford - or Indianapolis - expanding to provide enough slots for all these 7e7s in the teeth of public nimbyism?
Clearly, what is needed is to squeeze as much payload as possible into each flight (slot, route, ton of fuel..). Point to point will remain a luxury - which is as well, because the rising cost of each movement will demand high fares. The LH 738 operation might work out, but this has a limit - namely that the travellers who can afford $5000 fares are concentrated in places near hubs!