I know absolutely nothing regarding the plans for the 88s or 320s, but I've heard Airbuses tend to not age well. Furthermore, I've heard the 88s are holding up, airframe-wise, much better than anyone anticipated. I don't think the company would be investing as heavily as they plan to with flat panel upgrades I'd they didn't think the airframe could sustain a long term operational longevity. Apparently, the 88s are the most operationally profitable aircraft we own right now. Personally I see them in the fleet for a very long time. Fwiw.