Only time will tell, I guess in a few yrs we can do a side by side comparison. I can't remember any regional with flows in the past who have been in a better position than those without, but who knows. I do know plenty of guys getting hired from all regionals to all majors, LCC etc. While at an airline with flow you are less likely to play the field cause you have more skin in the game. Management would never use that to their advantage, or go back on their word of course!
How long do you project a yr 1 FO to make it to said major?
PSA's process is not "managements word" it is defined very strictly in a binding contract. I'm not saying mgmt would never try to get out of it but it wouldn't be as simple as "Colbert dropping the microphone".
A one year FO today could reasonably be at the major in 10 years assuming NO OTHER ATTRITION. At this time we are losing 8ish a month, which doubles the attrition from the progression agreement. 5 years could be a possibility.