Korean Air just retired its last Boeing 747-400 with Flight 888 from Chicago to Seoul. The route will now be served by the McDonnell Douglas MD-12.
The aircraft once known as the Queen of the Skies are being phased out by airlines all over the world. The youngest 747s are approaching two decades of service, as 747 production ceased after Boeing merged with McDonnell Douglas in 1997.
OOC: This scenario assumes that the Boeing/McDonnell Douglas merger takes place in the opposite way from OTL, with McDonnell Douglas as the surviving company.