I'd say the English Premier League has done pretty well, since they told the FA to "take a hike."
Then go ahead and do it. There is a reason why they don’t do it. College football is a very regional sport. Most people outside of the Southeast don’t care about the SEC. Most people outside the Midwest don’t care about the Big 10. Same with the Big 12 or the PAC-12. In the big TV markets in the northeast they don’t care about college football at all. So they would not be gaining anything by leaving the NCAA, they still only retain the same fan base. Unlike the Premiere League they can’t poach the best players from the NFL because they are professional players not college kids. They would then have to become an alternative pro league losing their college affiliation and the track record of pro leagues trying to compete with the NFL is not good.