If you can deliver one with reasonable spec that is range, price and fuel-efficiency you can sell a lot. It is size range where there is significant demand. A3

If you can deliver one with reasonable spec that is range, price and fuel-efficiency you can sell a lot. It is size range where there is significant demand. A321 planes mentioned have orders in thousands. And that is a lot for a plane. So well executed plane fulfilling design criterias certainly seem like reasonable mainstay.