There are approximately 40 DAL who are scheduled to return. 17 have left thus far for various other airlines or corporate positions. The number is out on the AA returns going forward. Based on industry hiring the number could reach 100 this year. Time will tell.
While it speaks volumes of JetBlue you must remember this is a business. Despite all the talk and emails about culture and NPS your compensation,benefits package and protections tell the real story.