A lot of corrections here:
* BRU already did have a B777 service in the past, as correctly stated SFO-LHR-BRU by UA. However, already for two years now, the LHR-BRU-LHR part has been operated by B763, and will most likely not return next summer as UA needs the LHR-slots for their round the world service ;
* Egyptair's sunday-service to CAI is normally operated by B743, but occasionally gets switched, mostly to B777 or A340 ;
* Delta's MD11s are no longer operating to BRU on the ATL route, and will not come back for the summer season neither ;
* Continental is still operating the B752 to BRU, and will only next month swap to B762 ;
* I don't get your point about the 6 A330/A340 services, the 7 B747 services, and the 8 DC10/MD11 services. You mean that is the number of carriers operating these aircraft into BRU?
I wouldn't personally be surprised if, at some point, SQ would switch their B744 into a B777 on BRU-SIN (which will become a non-stop from august, not via ZRH anymore) and become a new B777 operator at BRU.