Trust me George I know. RA stopped dogging the GTF's a little over a year ago. The change did not go unnoticed by me.

I fleet of the 320 series makes a lot sense for a lot of flying we do. the 321 is not a 757 though. I suspect that 15% is good but absent a clean sheet design we will probably shy away from signing on to fleet renewal with the current generation of jets. Maintaining or growing a given fleet, yes, but not total replacement.
With the amount of jets we need and the varied missions there is not fleet that meets all of the needs that will compete with the next get stuff. A re-engineing of the 320 makes good sense, but I do not know if DAL would sign on to replace the entire narrow body fleet for the savings touted.

Either way, talking of new jets is good. Signing on the dotted line for new or used growth jets is better!