Well written Jim.
I think the most important question one has to ask is what is the ultimate goal of another league? #1: Is it to provide entertainment, more jobs, experience, etc.? Or #2, would it be to have, as you said, a "Farm/D League", which allows the current 32 NFL teams a lot more depth and the ability to better develop more than the 10 guys the current Practice Squads allow for?
If the answer is #1, I think you nailed it, alternative leagues been attempted in so many different ways over the years, I think another one is bound for failure. Now if the answer is #2, I like it simply from the mere fact that it would allow NFL teams to develop players and ultimately put a better product on the field every Sunday. Injuries, early retirement and suspensions seem to be on the rise and those have forced teams into playing guys that probably aren't truly ready for the NFL. A D league would retain potential talent and prepare them for the next step.
I won't regurgitate all of your article, but a "D League" would also have a key element to it, that no other alternative league has had, just like baseball, affiliation with a current team and its fan base. I for sure would follow a D team like "The Green Bay Cartons", simply from the fact that the team would be comprised of players that could eventually play for the Packers. Fans are rabid about anything that involves their team and the future of it. The questions the NFL would have to ask themselves are: 1. Can all 32 teams afford to operate a D team? 2. Would having twice as many "NFL players" dilute the current product? 3. Ultimately, the biggest driving force for NFL owners, Will it make us money?