Desert Liner, the number aisles is related to safety. So 5-5 would probably never get approved. The 2-2-2 I specified has narrow seats and minimum width aisles. Also the double seats are placed at minimum pitch that wouldn't go well on 4-5 seaters.
The additional cabin provides credible comfort & luggage space for flights up to 9 hours. It's a little bigger, more range, better cargo and more comfortable then the 757s. Combine that with CFRP fuselage + wing and new gen engines and I doubt operators will go for expensive 40 tons /90.000lbs heavier 787's/ A350s, that provide an enormous boost in capasity on top of that. I don't see how that can be an economic solution for the 757/762 sized medium haul replacement markets. It would be great aircraft on the wrong mission.
Side kick: I wouldn't be surprized if Boeing makes a deal with the Japanese to convert the 787-3s orders into 787-8s and move on with the 787-10 instead. A win win it seems.. The 787 simply aint a <5 hr aircraft.. neither are the A330 (ask Qantas) and A350..
