I found these pics online last October from some professional aviation site (can’t remember where).

Boeing is feeling the market for two concepts....one a new narrow body, and the other a “pseudo-widebody” (Dual aisle, but inside a fuselage only slightly wider than a 757 or A320. Ironic, given that the 797 would be sold as a replacement for a narrow-body and a “sort-of” wide-body....)

This pic shows two potential layouts: a short-wing small engine, or a long-wing big engine. The fuselage is an oval, giving the potential for dual-aisle the full length of the cabin, OR a much wider single-aisle, still with 3 x 3 seating in economy.

The cargo hold would be the narrow part of the oval. This would reduce frontal area and wide-body drag, but still allow a standard AKH baggage pod, currently used in the A320 family.

I could see an airline going dual-aisle in First Class, with a single aisle in coach.

Boeing’s dilemma: trying to determine realistic sales market, and which version. Development would allegedly take 9+ years, and I forget how many billions. Boeing is afraid the market may have been largely absorbed by A321 NEOs and (ugghh) 737 MAXs, leaving perhaps only 400-600 airplanes needed...for the routes that 767s and 757s do.

Interesting concepts. Curious how the artist’s concept in profile looks a lot like a 757. I fear they will take too long, and decide there’s no market for it.