I see the A380 as having had the stars lined up against it. First, and most important, Airbus really, really, REALLY wanted to build it so they could snatch some sort of title from Boeing. And that mindset led to several strategic errors in addition to a lack of realism about what the demand for it really would be. The first one was a lack of appreciation for what was coming, I. e the 77W and the 787. That is understandable since nobody really knew. But not knowing led them to be sloppy in optimizing the design for the plane they were building, figuring its size would be enough to make it efficient enough to be attractive. They certainly did not expect that before it was flying that Boeing would have a twin engined plane (the 77W) that would nearly match both its range and economics, or that they would come out with one (the 787) that would actually beat its per seat economics in a much smaller plane. They obviously had watched Boeing for years sell 747s at enormous profits because it had no competition, and were itching not only to give it competition but grab that gravy train for themselves. But by the time they had their plane the gravy train had ended, because it was not the size of the 747 that put it in its own class but its range. And the handwriting was on the wall even before the A380 was launched, that smaller planes were coming that could match or exceed the range of the 747. And so by the time it was flying it’s only real advantage was to airlines flying to slot-constrained airports, and the only airline that really took advantage of that was EK, whose hub was very limited for the number of passengers that they were trying to put through it. Had EK had more hubs they probably would not have bought anywhere nearly as many.
So if the A380 been more optimally designed, with a smaller, lighter wing instead of one optimized around future, and not present, needs, and perhaps a lighter fuselage, would it have been more successful? Probably slightly, but I think it still would be going down in flames now. The 77W, 787, A350 and A330NEO are just simply less risky for most airlines as they are so much easier to fill year round, and their economics are competitive with or even beat the A380s. And when demand is high, you can increase frequency, and reduce it when it slows down. That beats flying the A380 half empty.
In the widebodies, nearly every successful model has been designed as a base model and a payload for range stretch, That allows each component to be designed near optimum or the same for the 2 models. A MTOW increase is usually cashing in some reserves in the initial design.
The A380 was not tightly designed for the 388 requirements, but with lots of 'future', also there is usually a 'natural' gap between models, something like 20% more capacity. To stay closer to familiar territory going above the 744 just by 20% is a lot less risk than a 35% jump. the 380 positioned itself as far larger than the 744, requiring bigger hangers, different gates, far larger insurance costs, new approaches to ticketing, boarding, and baggage. If an A380 is later arriving does the whole hub wait, otherwise so many passengers needing rebooking, etc. If it goes Tech, what a mess.
Only 9 airlines have ordered 10 or more, 3 of those received their first plane after 2012. It is telling that LH, AF, QF, QR, and BA have not done top off orders since 2012. Except for the 20+16 EK order, it has been 5 years since a dozen orders in 1 year. The airlines said by their purchases that they needed other planes instead. It is actually quite sad how they badly missed the sweet spot for that model. In contrast, the 787 was positioned at a good sweet spot, it blocked above the 330 into a position of excellent sales.