Emirates will add a 3rd service to BHX only after one is in place at MAN. If you look at the figures that Pete's posted every month, you have to factor in MAN was consistently 3000 to 5000 passengers per month ahead of BHX even before the A380 was placed onto one of MAN's services.
As it stands, EK haven't been using the 442 seat 77W at BHX for very long - they would need to see sustained loads using that prior to the next decision of A380 or 3rd daily. That's likely to be October next year at the earliest or more likely March 2012 (depends on fleet availability)