This A370 concept is significantly wider than e.g. a A320.
The first sketch was A370-800 has a more typical 231 seats 3 class medium rane configuration for flight > 6 hrs. This -900 stretch version has a more leisure kind of single class cabin, seat >300 passengers. At that point you really need a wide aisle during boarding / de-boarding but also during flight. If people can't pass each other, bump each other during flight in the aisle things can get real uncomfortable. source: keesje
The idea of this cocept would be to extend NB reach up to 300 seats and 5000NM....
If such an aircraft could be made weighing less than 80t (OEW), that is 30% less than typical WB's reducing operating costs in every area.
Your fuselage is 178 inch = 4,45 m diameter. That's 50 cm wider and 31 cm higher than an A321 fuselage. Can it compete with the A321?
The A321 has an OEW of 51 t, your idea an OEW approaching 80 t. I also wonder if 60 m length isn't stretched too much.
I believe the question is what is better:
a) An A321 with a 45 m wing plus a five meter stretch, both MTOW of 120 t. The five meter stretch would be two meter longer than B757-200, but five meter shorter than B757-300. Probably I imagine this too easy. Which leaves us with b).
b) If one increases A321 fuselage width by 30 cm and height by 11 cm one gets a circular fuselage of 4,25 m diameter. Maybe height should also be increased by 30 cm for a bigger wing box. I believe fuselage diameter increase has to be limited to 30 cm, fuselage length can be maybe 3,5 meter longer.
Let's say three types: A321 length (44,5 m), a five meter stretch (49,5 m) and another model with a further 5 m stretch (=B757-300 length = 54,4 m). I doubt OEW would reach 80 t. B757-300 had 64,3 t OEW.
Somebody once mentioned that one tyre supports only 30 t. That may limit a narrowbody with usual gear to 120 t. But I'm not qualified to judge.
Even though I agree to your 1,5 aisle concept, 50 cm wider is overdoing it. I believe OEW should be around 70 t. Can it compete with 51 t OEW A321? Maybe yes, but probably not with a wide margin. May not be worth the action of a clean sheet.
Transpacific may need more fuselage diameter for the wingbox and longer wing. 80t OEW may be right for it.
And I assume economy passengers will appreciate more armrest for more than 10 hour flights, which your fuselage enables.
For limited range A321XLR is good enough. If a new wing / more MTOW/ stretch is possible, so much the better.
A clean sheet with your proposed fuselage for transpacific traffic sounds about right to me.
I also believe that widebodies are good for transatlantic because of cargo. I believe your plane is something for beyond 10 hours flights.
Why would Boeing or Airbus design such a plane?