I still like the 747

Since the arrival of the 747-400, several stretching schemes for the 747 have been proposed. Boeing announced the larger 747-500X and -600X preliminary designs in 1996.[81] The new variants would have cost more than US$5 billion to develop,[81] and interest was not sufficient to launch the program.[82] In 2000, Boeing offered the more modest 747X and 747X stretch derivatives as alternatives to the Airbus A3XX. However, the 747X family was unable to attract enough interest to enter production. A year later, Boeing switched from the 747X studies to pursue the Sonic Cruiser, and after the Sonic Cruiser program was put on hold, the 787 Dreamliner. Some of the ideas developed for the 747X were used on the 747-400ER, a longer range variant of the 747-400.

After several variants were proposed but later abandoned, some industry observers became skeptical of new aircraft proposals from Boeing.[86] However, in early 2004, Boeing announced tentative plans for the 747 Advanced that were eventually adopted. Similar in nature to the 747-X, the stretched 747 Advanced used technology from the 787 to modernize the design and its systems. The 747 remained the largest passenger airliner in service until the Airbus A380 began airline service in 2007.