AA-STL, BA to STL sounds good to me too, but it's likely never going to happen. AA will take care of the STL-LON flights.
Blink182, all BA 747-400s are based in LHR. DFW would need to be added to the LHR cities before BA 744s would land in Dallas. And I totally agree with you, if NW/CO/DL is approved, BA/AA will have a fit if they aren't. NW/CO/DL will offer them a HUGE advantage over AA and US/UA, and AA/BA will argue that they should also have some sort of huge advantage. Then again, I doubt that NW/CO/DL is going to be approved.