Actually, NBC, and NFL bailed out the AFL, as it was on the verge of bankruptcy. The league definitely has a niche though, and unlike the other league's the AFL didn't pick NFL markets to have it's teams located in, they picked small cities with a decent sized arena's, and played after the NFL seson was over, with a completely different set of rules.
Now the AFL has a minor parternership with the NFL, and a lot of NFL owners, and former players own AFL teams, and have placed them in NFL cities, with a full complement of air time, and marketing.
As far the USFL, and the XFL are concerned, the NFL didn't exactly raid the XFL as some of you think, there were only about 15 players that made it from the XFL into the NFL, and I think now maybe only 3 of them are still in the NFL.
When the USFL folded, the NFL raided the USFL for players, and there are a number of former USFL'ers that are in the Hall Of Fame, and some may be on the way, but a lot of them contributed to their clubs, when the league broke up. Steve Young, Jim Kelly, and Reggie White are just a few of the USFL'ers that have a bronze bust in Canton, and Reggie White will get his this year.
The USFL tried to compete with the NFL by luring players away from the NFL, and drafting players right out of college, and not letting them even taste the NFL. Unfortunately there wasn't good enough coaching, and the lack of star players hurt the league, considering the money they were spending.
The biggest thing that hurt the USFL though, was the lack of television exposure. There wasn't a rebel network like Fox back then, and ESPN wasn't the monster that it is now. Had there been the exposure that exists now, they probably could've lasted longer than they did, because they were luring away some good talent out of college.
They took Heisman winner's Herschal Walker, Mike Rozier, and runner up's Steve Young, Anthony Carter, and Marcus Dupree straight out of college, lured Doug Flutie, and Doug Williams away from the NFL along with a few other stars, and along with the money they were shelling out had the exposure been there, no telling what could've happened with them.
The league also produced some good NFL coach's, most notably Jim Mora, and Jack Pardee (even though he had prior NFL coaching experience).
All in all, the NFL is a monster that only college football can go head to head with, and walk away with all of it's bearings.
NICE