Personally, I think a developmental league could survive. Any league designed to make money will likely fail.
There is another developmental league that played last year and a similar one starting up this year or next.
The concept of having a 4 to 6 team league, all co-located on a "campus" - backed by the NFL - would have success. Each NFL team would contribute $1 million, which is NOTHING to them, and the league would have a budget of $32 million. Give each team $5 million to pay for everything: salaries, dorm rooms, meals, coaches, trainers, admin staff, etc. The extra $2 million would go towards the 'league front office' (for all other expenses such as electric & water bills, referees, etc). Players would have minimal salaries ($1,000/week or so) and each team would have one or two full-time/year round coaches (making decent money, $150K or so) and the rest would be brought in before the season started on short-term contracts. Just a few ideas here, nothing set in stone. But w/ the backing of each NFL team putting in $1 million it would develop a lot of talent for a league that needs OL's, QB's, and DL's badly. This would work with probably $500K per NFL team.
This would not only allow players to develop, but coaches, trainers, league officials, front office employees, interns, etc.
A pro football league trying to make a profit is going to have a tough go.
