I'm sure this is a VERY complex issue. But two things come to my mind.
1 - Maintenance and tooling for the 747 series has been around for a long time; so moving to 380 would likely be a much bigger deal in that regard than moving to the latest 747 variant.
2 - Fewer airport options for 380 vs 747 means less flexibility of how the fleet is deployed.
1 - Maintenance and tooling for the 747 series has been around for a long time; so moving to 380 would likely be a much bigger deal in that regard than moving to the latest 747 variant.
2 - Fewer airport options for 380 vs 747 means less flexibility of how the fleet is deployed.