Originally Posted by CTJoyce

Delta has 100 confirmed 739-ERs on the way and they start taking delivery this year. We also know that the NW A320s are hitting the end of there life which means that 68 Aircraft over the next 5 years or so need to be replaced. Now Delta could replace those aircraft with 739s for parts commonality, however that now means you have air crews and MX crews that now need to be retrained on the Boeing aircraft. So you now have to decide is it cheaper in the long run to take A319 / A320 crews and drop them into A321s and continue to have two different air frames worth of spares on hand, or do you take those crews off the line and spend the money to send them to the school house for 3 months?

We also know that in the Delta Pay scale there is a pay grade specifically for the 739 that fits between the 73G/8 and 752/753/763 brackets, and there have been multiple sources saying that there has been talk about adding the A321 to the 739 bracket suggesting that Delta is in fact ordering A321s.

Personally I would prefer an entire fleet of Sky interiored 739s over A321s but that's just me.