The 797 could be built on elliptical lines as depicted below in model "a". Standing at the front of the airplane and looking back is an elliptical cross section. The center line from A port side to B starboard side would be at the seating passenger level. The ceiling crown could be about 8 Ft from floor to crown. Below the center horizontal line is luggage storage, ancillary freight and aircraft gear.
Fig. 1 The "Winging It" 797 MOM/proposed body cross section.
The penalty for the design is limiting freight space in the belly. The shape could increase lift (lifting body concept) without having any significant drag increase. Pair the design shape above with a taller landing gear allowing appropriate engine power could make this a world beater and tough to copy as Airbus is known to do.
The other trick Boeing is working on is reducing weight with a dual aisle arrangement. The elliptical body may do this as its lighter than a 787 frame. The sketch above is exaggerated as to what an actual body cross section would look like as Boeing would push the side in by inches in proportion to the elliptical height as being more likely than this example. However, Boeing would like to find about 20 more inches across from a circle design. All of this enhances the passenger and flight experience for which many airlines are seeking.
The Boeing doodling in the lab CAD computer can make a paper airplane that works well as the 787 did. All kinds of shapes and sizes are tested first at lab level and then it moves into a wind tunnel model for validation of flight characteristics from the CAD tinkering.
This could show up in Paris later this month but I doubt it. Paris will be all about the 737-10 announcement.