Hopefully the horror film happens during the process of trying to get the aircraft certified to carry 3,000 people in 28" seats. During the evacuation testing, passengers forget to exit and simply go cannibal inside the aircraft.

IIRC, the original business case for the superjumbo relied a lot on slot-restricted airports. The demand curve into certain max-capacity airports would drive yields high enough that a big expensive four-holer still made sense to operate. Since there are a couple hundred A380s in the air, and they will be with us for decades to come, perhaps they will continue to be useful on those select routes. Same for the 744 and 748...