Theoretically you could get 16 Heavies down in 30 mins with a few minutes to spare.
Applying 4nm spacing generally gets a landing rate of 36-37 per hour.
TBS aims to get 90s between Heavies.
Adding A380s would lower the landing rate, but ideally you'd bunch them together as there's no wake requirement between A380s. You could even get to a stage where the overall landing rate would go up because of that.