Here is one mention of the 320 in a September Flight Ops Comm, I'll paraphrase:

319s are young. We have some 80s/early 90s 320s coming up on their life cycle checks. If Airbus is unable to extend those life cycle checks (and why would they want to?) then we will park these 320s in 2015.

And we're overstaffed on A320 Bs.