A318
I have from the horse's mouth that Airbus strongly wish to get the A318 cleared for LCY operations.
On slightly less good authority I believe Airbus contend that the 318 will offer greater range out of LCY than any other type, and will therefore open up an entirely new range of destinations.
So it would be a major plus for the 318 programme, in view of the difficulties with PW6000 power and the low overall level of airline interest in the type.