You're right, it would never fly, but probably not for the reason you think. A company like Boeing is good at writing off large losses, after all. However the

You're right, it would never fly, but probably not for the reason you think. A company like Boeing is good at writing off large losses, after all. However the problem is the customers. By the time they design and build an entirely new narrow body plane, the customers would have long since modernized their fleets with planes bought from other manufacturers like Airbus.