BA usually has 2 daily nonstop flights from Heathrow to Philadelphia (BAW67/BAW69) 67 being operated by a 777-200ER and 69 operated by a 787-9. But since they are giving up the 69 flight to American they won’t be flying the 777 to PHL. (Or the 787) Fortunately they are sending the 747-400 for the 67 flight, it will be the only 747 that flies to PHL. The flight being given to American is AAL737 which will be operated on a A330-300. Sometimes Fedex uses Kalitta’s 747 for charter flights in the winter.
So American airlines will takeover that route with the American airlines 772 and British airways will use a 747 to replace the 772, but British airways will keep operating this route right, nice article