The year of the 797 is 2018. The 797 honors the laws of physics and is not competing with Airbus with this offering. The 787 may have been announced in 2003 and first delivered in 2011 eight years later, but the smaller 797 or NMA will complete itself within five years instead of eight years suggesting a 2024 entry into service.
A take from the Paris Airshow from "Aviation Week": June 2017
"At the show, Boeing did, however, confirm several new configuration details, including the use of a fifth-generation composite wing, a “hybrid” composite fuselage, next-generation digital architecture and super efficient, very-high-bypass turbofans. A conceptual graphic and side-view profile also showed a 757-size aircraft clearly displaying a meld of 777 and 787 design features."
Even though considerable homage was paid to the 757 configuration, going twin aisle makes the 797 go wider than a single aisle and is narrower than a 787 ,as mentioned by several Winging It postings. The reference of a hybrid composite fuselage becomes an enigma for most aviation geeks. It sounds like the body will have design aspects which will lend to using composites in critical areas for strength, especially around window areas and then inserting aluminum alloy panels in non critical strength areas. The imaginary view implies a panel construction similar to the Airbus A-350 presentation but have a "C"shape panels in a critical window area allowing for its width at a mid-body key point.
The "aluminum alloy" panels will shape the remainder of the body. The over-all weight reduction will make this mid model the most efficient it can be when using hybrid design points as well as hybrid parts points for the 797's body outcome. The lifting surfaces should all be composite. An estimated 50% composite body including wings is the "hybrid" outcome.