The reason why minor league baseball works is because, for most of the season, the majority of the payroll is handled by the major league affiliate.

Major League Baseball teams have a 40-man roster, with only 25 men active. This means that if everyone is healthy, 15 players are designated to the minor league affiliates. Most, except for those that really need specialized coaching, are assigned to the AAA franchise. Usually, of the 25 players you see when you go to the Salt Lake Bees games, 10 of those players are actually being payed directly by the major league team at their regular pay. The MLB minimum salary is over 500,000. While the minimum AAA salary is about 2200 per month. Most AAA players that are not on the 40-man roster have a split contract (AAA/MLB) that pays them more, with the MLB team often paying the bulk of that contract. As a result, AAA draws good crowds and fans seem entertained. Most owners of AAA teams, and some of the owners at the lower levels, make profits. Nearly every AAA baseball team plays in their own stadium. Few, like Smith's Ballpark in Salt Lake share their ballpark with the local college team.

The NBA had not followed this model, therefore players that don't make the NBA, like Jimmer, maker more money overseas as opposed to struggling with the D-League. The D-League usually only has 2 assigned from the NBA parent club...(NBA D-League 14% of the roster with no split contracts, vs AAA baseball which is about 40% of the roster plus split contracts.)

If minor-league football is going to work, the NFL needs to adopt a model similar to MLB and stay away from the failed model of the NBA D-League. The NFL would need to pay 20 players on the 53 man roster at the NFL minimum or higher, plus have some split contracts. I think this could work sharing stadiums primarily with Major League Soccer or FCS teams at first, but in time most teams would have their own stadiums.