I don't think it would do this at all. The haves would out pay the farm team to keep the players. The have not's are more likely to lose the players that are good enough to go.
This is all assuming that the farm teams have better strength/conditioning, overall prep for NFL than colleges.
Yeah probably so, was more thinking along the lines of the previous system. In baseball you see Vandy and others being able to do that now, albeit with scholarships rather than NIL.
At the end of the day, I don't think a farm system works in NFL. You only have so much wear and tear on your body, unlike baseball. Any secondary league to the NFL will just be the guys who simply could not make it. And I really don't think a league like that can ever amass enough fans to last, unless they get REALLY innovative with the marketing. Seems like they'd need to either be in NFL cities and play off the main team closely, or be in smaller cities and create some rivalries similar to what the Sun Belt has done (jury is still out on whether that works). Neither of those really appeal to me at the pro level, maybe they do to other people.
Only reason pro sports works is because you have city/regional rivalries and the best players in the world. Take away either one and it falters. Obviously they lose the latter, so they'd REALLY have to play up the former, and create like 'state' teams or something, maybe based on population. Maybe make a certain population be the max, so say it's 25M. Florida can have one team, maybe Georgia/South Carolina/Alabama have one. I don't know, just brain storming. And they play in different stadiums throughout the area.