I have flown on PS from JFK, on L-UAL old and new UA configuration, but I also have flown on DAL 1st class and JB A321 Mint. JB Mint was by far more superior service when it comes to quality of both seat and customer service.
But the question is not how comfy the seat is or how the plane looks like, the question is $$$. If the data shows, that we are loosing money, despite our improved seat configuration, we need to make changes. Get new customer service (ie.FA - well that is out of the question, we have to wait till L-UAL FA die off) charge more $ for the service, or shift service to more profitable routes, were JB does it all the time.
Just the same way I feel about B737; it's a total junk from 60s, noisy, small flight deck, not design for oceanic or transcon flights, but as long as UA makes money and pilots are employed making good money, who gives a $hit. It's time you guys drop the melancholy of old unprofitable L-UAL flying, move on and focus on the future, or just simply retire. I wouldn't worry about what DAL is doing, because I don't work for DAL, and as long as we both don't get in each other ways, and don't fight for each others pax, we are doing OK. I think the big three finally figured it out, that stilling each others flip-flops and shorts is not the way to do business. Self regulate, capacity discipline, and stay from each other network is the way to go. Now lets keep UAE sand box d1p$hits away from my playground, and don't let them use our toys from Boeing or Airbus using our money from Ex-Imp bank. Don't cry about PS from JFK, focus on what's important.

JetBlue Mint: Flight Review: JetBlue Mint New York (JFK)- Los AngelesThe Points Guy
https://www.youtube.com/watch?v=etqBdh8JjC4