I can't think of any Boeing commerical aircraft that has been a flop. Variants yes, such as the 737-600, but not models. Boeing has done the market studies and if there is enough demand then they will build it. It won't be as expensive as the 787 but they certainly won't be giving it away. It's a brand new plane, not an end of life product like the 737-900 and A321ceo Delta ordered at cheap prices. R&D, tooling, etc must be paid off. After that the price can be lowered. We have finally seen production costs of the 787 decrease and Boeing has been able to offer it at a competitive price and it has kicked the A330neo in the rear. Operators have even canceled their A330neo orders and bought up the 787-9 instead. That's really something that a new airplane can compete on price against a rewarmed plane developed in the 1980's.