Realfish,
Emirates already do flights from BHX to many World destinations.Im off to the Maldives with them from BHX soon.To DXB then the connecting flt to Male Maldives.
They do the same to Australia.No European airport has any EK flight direct to any other place but Dubai.
In relation to runway length and MTOW. It all depends where you want to fly and conditions.
A 380 at sea level needs about 2,800metres on MTOW. As your airfields get higher or hotter you need more runway length as the air gets thinner.
BHX is about 325ft above sea level so a bit more is required.
Mr Keehoe said last year that the runway extension at 350m (taking it to 2,950m) would enable planes to fly to 95% of the long haul destinations it wants.
So all of India, parts of China, Hong Kong, Vietnam, Sri Lanka Thailand (just) etc should be reachable..However probably not Malaysia, Phillipines, Japan or, Indonesia.
Think you would expect the first service to benefit would be EK, perhaps launching A380s to mark the opening of the extension in 2014..unlike before they would not be weight restricted.
Nigel