Well the CFM56 was not to be on the A318 either.
Following the multi year delay in the development of the PW6000 engine, Airbus under pressure from airlines was forced to fit the CFM56 on the type.
The A318 first flew back in 2002, and the PW6000 is just becoming ready now 3 years later in 2005. It could be argued that several existing A318 orders including from BA
, Air China, Egypt Air, America West were all swapped to other Airbus models as a result of the delayed introduction of the type and engine.