I was just reading the other day that SFO is rapidly approaching mandatory slot control, several years earlier than expected. I forgot where I read it but here's some info on the FAA site:
https://www.faa.gov/about/office_org/headquarters_offices/at...SFO has given up on building another runway, which means the only way to grow is with larger airplanes. Some other large US airports are also likely to reach maximum movements in the next decade, and I imagine the same is true globally.
And then on top of that California appears to be backing away from HSR. The biggest cost (legally, politically, financially) for HSR was land acquisition, the same reason SFO canned plans for an additional runway, and the same reason it's not feasible to expand metropolitan highways. Because traffic will only get worse, making OAK and SJC increasingly less attractive to those living on the peninsula, I'm guessing that SFO will see more A380 service than less.
Not that it would make any difference for A380 viability, but it's understandable why Airbus, Emirates, and some others held fast to the promise of the A380 for so long.
A week ago HN user Xixi linked to an article, https://leehamnews.com/2015/12/11/bjorns-corner-twins-or-qua..., arguing that the 4-engined A380 is actually more fuel efficient and less costly to maintain than comparable 2-engined aircraft like the 777 because 2-engined aircraft need overpowered engines. According to this argument what really killed the A380 was exactly what Emirates was upset about: no manufacturer was willing to sell an engine upgrade, so the A380 would be stuck with older generation engines while both contemporary and new model aircraft benefit from newer engines. I guess the engine manufacturers' calculus is largely concerned with volume, but it's also a sort of self-fulfilling prophecy.
After reading that article I wasn't surprised when, perusing the Wikipedia pages for the new A220 (Bombardier CS300), Embraer E-Jet E2, Russian Irku MC-21, and Mitsubishi Regional Jet, I discovered that all the new planes at the small end of the market--a market that both Boeing and Airbus turned away from just a few years ago--are sporting a variant of Pratt & Whitney's new geared turbofan. It seems like in today's environment it's the engine that makes or breaks the plane.