I don't think there will be a radical design change, although I expect to see major developments in materials and engine technology being incorporated - GTF
certainly, but what might come between now and 2020-22, when the 797 is likely to enter service.
1. As to market, the 100-130 seat market is likely to be quite full, with several different types competing for it; I see there being three fuselage sizes, taking the aircraft from about 160 (2 class)/190 (1 class) to about 240 (2 class)/270 (1 class); the aircraft, while primarily aimed at existing 737 routes, will have an ETOPS option and should be able to cover up to 4,000 miles, enough for short transatlantic hops (E Coast-Dublin, AMS
2. Fuselage; abandon the current single aisle design, which - let's face it - Boeing has got pretty good value out of! I see the fuselage cross section being closer to the 767: 2-3-2 in a standard layout, with 2-4-2 being available in a high density layout.