Prospective being the key word. I won't go into it all, but not a fan of flow through programs and the entitlement and eventuality it produces.
You should tell that to one of the current Eagle pilots flowing that has dedicated 16-20 years of his life to AMR, now AAG. You know.. the guys that lost their CA seats and stagnated their careers for YEARS due to hundreds of AA pilots that flowed back to Eagle and occupied our seats (as part of the Letter 3 deal). I spent several years flying with AA flow-backs here as well which stagnated my movement almost a decade ago. Flow was a 2 way street for Eagle/AA. Our pilots could go up, they could come back if they furloughed, and they did. Funny how a bunch of people over there forget "that" part of the deal, which gave a home to AA guys at our highest CA pay rates to their furloughed pilots when they needed it, yet now the mainline guys have a problem with flow since their buddies can't get hired. Most guys get it, it's typically Usair people nowadays complaining about it for the most part since they have no idea about how any of the convoluted "letter 3" situation came to be.
Then, back in 2011 ALPA decided to give up the rights of us flying our own American Eagle aircraft in a "grievance settlement" with AMR to get a flow deal for more of the pilots here at Eagle that weren't part of the 824 arbitrated agreement for harmed flow pilots. This covered all pilots on property up to 10/2011. Supposedly it was just going to provide our more junior pilots with enhanced job protections and no harm would come from it. It was just a legality/paperwork thing the company needed if we were divested they claimed.. Yeah.., since that screw job deal was made via ALPA/management our fleet has been decimated and handed out to multiple other carriers due to that messed up back-room agreement that allowed our Eagle flying/aircraft to transfer without us or our contract attached with it anymore. The pilots at Eagle earned their flow rights to AA through taking in AA flow-backs into our CA seats, YEARS of stagnation and displacements, and now, loss of our aircraft to others due to that grievance settlement/flow deal with AMR. These guys here have earned this flow-through a lot more so than some person hired off the street who has invested nothing into AA.
Maybe not the new hires that just walked into this newest post bankruptcy "eNvoy" flow deal without paying for it, but the rest of us have paid and sacrificed for many years for this court ordered flow & the current contractual flow rights we have paid dearly for. Some more than others.
As far as PDT and PSA, I have no idea what kind of agreement they had or didn't have with USair before the merger. One of those guys would have to comment on that..