Though they do have 777's in their fleet, the Emirates business model is built mainly on a Airbus fleet. I havent really understood why they went in for the 777's of which they have around 9, as they also have the 330-200's, which are similar in size. Perhaps they might phase these out?
i think the Emirates route structure is more suited to the 200-300 seaters. I hear they have also ordered the A340-500's which i suspect will be used for high-freq services to the US, which fits in with my theory perfectly.
I dont see the 744's fitting into EK's route structure at all. Even the A3XX order seems a little baffling. Perhaps they intend to operate these super-jumbos on 'slave flights' to India/Pakistan and South-East Asia. And anyway, i dont think the A3XX is all that bigger than the 747 and its derivatives; not the -100 version anyway.
The reason they went in for the A3XX is probably for reasons of fleet commonality more than anything else. They felt that they need a larger aircraft around 2005, and it makes sense to stick to one mfr.