Bearfoil,
The 787-6...never heard of that?! The 787-3 has been shelved for a few years until Boeing gets all the gremlins eliminated with the 787-8.. then the 787-9 will come up for certification..
The Dreamliner program in fact is the basis for the next single aisle airplane..it would be all composite...passenger/cargo load similar to the 757 and fuselage factor would be pretty similar.. The A321 NEO can do it for a bit less in cargo and passenger..transcon and TATL. The studies right now are checking if it's viable to do a Single Aisle with a 4-3 seating arrangement...meaning a fuselage a few inches wide. or 3-3 arrangement with a fuselage a bit longer..the economics would be superior due to new engine programs from RR, the GTF would be like in revision 2-3 and the CFM well, let's see how they can cope with the core temperature first...I guess that they will use a huge amount of ceramics inside the Leap-X to accomplish what they have promised in the new engine..
Regards