Boeing Y1, to replace the Boeing 737, 757, and 767-200 product lines. The Y1 covers the 100- to 250-passenger market, and is expected to be the second Yellowstone Project aircraft to be developed. Boeing submitted a patent application in November 2009, that was released to the public in August 2010, that envisions an elliptical composite fuselage, and likely signals the company's planning for the 737 successor. In early 2011, Boeing outlined plans for a 737 replacement that would arrive in 2020. However, the development of the 737 replacement was pushed back with the decision to launch the 737 MAX, an updated and re-engined version of the 737 Next Generation, in August 2011.
Boeing Y2, to replace the 767-300 and -400 product lines. It may also replace the 777-200. It covers the 250- to 350-passenger market, and was the first completed Yellowstone project, coming to fruition as the Boeing 787 Dreamliner. Y2 initially referred to the highly efficient, more conventional, baseline aircraft for the Sonic Cruiser, which was project "Glacier". The Dreamliner competes with the AirbusA330, A340 and later A350 families.
Boeing Y3, to replace the 777-300 and 747 product lines. Y3 covers the 350–600+ passenger market, and is expected to be the third Yellowstone Project aircraft to be developed. It will compete with the Airbus A380 family as well as the largest model of the A350 family, the A350-1000, scheduled to be introduced in 2017. In June 2010 it was reported that Emirates, which has the largest fleet of 777s, was in discussions with Boeing about plans to develop a new airliner to replace the 777.