Orders can't just be shifted to Airbus, as their production lines are fully loaded for years to come. Also, there is little desire to make Airbus a monopolist. The problem basically started when Boing was merged with McDonell Douglas, as this created the duopoly which now has the market trapped. And of course it creates a huge amount of problems for all the airlines which ordered and planned for new planes which have the same certificatation as their existing 737.