If EK could get rights via MAN to the US, I have mixed feelings as to what would be the most suitable destination.
On the one hand, MAN produced data showing that NY was their most underserved route, but this included leakage i.e. pax from the catchment area not using MAN at all to get to NY. Personally, I feel the present 2 x B757s under values the route but it's anyone's guess how AA & UA would react if EK were to start. There again, EK would be attracting almost entirely O & D traffic due to the lack of connectivity, but there would be potential for attracting pax that don't currently use MAN.
There's a certain attraction in a secondary city route such as Boston, but would there be enough demand and yield for one of EK's large a/c?
Is it conceivable that EK might consider BHX as a UK transit point, providing a third flight for Dubai - BHX and extra capacity for BHX to New York? I doubt it myself, but you never know.
Perhaps transit to the US through MAN won't happen anyway (apart from PIA)
but an interesting scenario if it does.