1. A320 has same cabin crew as A319 as EZY have 156 seater version.
2. A319 can fly further than both the A320 and A321.
3. An LPL-AGP in August is much more lucrative on an A319 than two BFS, AMS etc. rotations.
4. Converting takes not even a a couple of days and if they wished to convert ALL crews from BOEING to AIRBUS then the A320 series really won't bother them much.
Overall, there are not that many problems with the A320 and A321s in the EZY fleet and we can probably expect the airline to increase these with their A320 SERIES order of 92 extra - not not A319, but A320 SERIES.