Since the 747-400 was made, many more types of 747 have been suggested. Boeing said that they would make the 747-500X and in 1996. These new planes would have cost more than US$5 billion to design and make. Airlines did not like it enough, so Boeing decided not to make the planes. In 2000, Boeing said it would make a 747X to rival the Airbus A3XX. However, airlines did not like the 747X enough, so it was cancelled. A year later, Boeing began concentrating on the Sonic Cruiser. The Sonic Cruiser was stopped, so Boeing then focused on the Boeing 787 Dreamliner. Some of the ideas that Boeing had for the 747X were used on the 747-400ER.