See, that wall is not a problem when you are in a duopoly. You will need to jump the wall only if your competitor jumps and why your competitor would jump if you can pocket the 8.5 billions and sell the regular stuff?

That was what Boeing and Airbus supposed to do: Sell the a320Neo and 737MAX for as long as possible and stay away from the wall. Now that Boeing screwed up, they may be forced to jump the wall and Airbus will have to follow. On the other side of the wall, they will sell the same number of planes.