NFL Europe was in fact the NFL's minor league. It was developmental players and practice squad guys. You can argue it went bankrupt because it was Europe, but it still had 0 viewership in the United States.You make a lot of claims in this post, but you don't back it up with any reasoning at all.
Why would a "minor league" football system go bankrupt in one year's time?
Why would it only attract 2nd rate high school coaches and players?
Truth is, we don't know how it would work out, but if college football suddenly vanished over night I assure you developmental leagues would sprout up.
The USFL was very popular and made money but ultimately went bankrupt.
The truth is most (if not all) D-League teams lose money because it's all players not good enough to even make the 11th spot on an NBA roster. This is why teams like the Pelicans who can't necessarily afford to spend money like the Lakers don't have one. If you factor in salaries I bet most minor league baseball teams don't make money either. Maybe I'm off by "one year" but the point is the same... it's not the NFL, no one would watch... it would be right there with the XFL and so on. Players would be better off doing the "overseas basketball" thing by just playing in Canada.
There's no way to back either way up, but basing it off everything else I'd bet it would fail and this is why it's never even been considered. I just don't see anyone who can coach in name brand leagues like decent NCAA programs or the NFL would move to the "minor league NFL"...
I personally would love another NFL Europe though, but again that would be players already in the NFL. Seneca Wallace type of guys and Anthony Dixon starters. There needs to be football in the spring somehow. 18 year olds should not be in professional football.