I would not hesitate to jump to AA if they (a) draw a line in the sand and say they are committed to keeping RDM earning based on miles flown and/or (b) start flying into my regional airport. So in this regard, AA could earn my business.

I am intrigued by DL's foray into five different "classes" of service. I'd like to see a US airline get into true premium economy so maybe this is a first step towards that. I think there is a gap between E+ and lie-flat business that I would be willing to pay for. Generally I despise what DL has done to FF programs but it looks like they are starting to get creative.