Re EK, the drop in cargo space and how any excess cargo will be dealt with is an interesting point.
On passenger capacity, perhaps the most significant aspect is that the A380 has 76 J class seats compared to 42 on the B777. And 14 F class compared to 8. (I think the evening flight is a 3 class 777 now, isn't it). That is certainly a vote of confidence in an airport that in the past has been labelled by some as having little demand for premium travel.