Since its founding, the N.C.A.A. has operated with a business model that defined the college athlete as an amateur. Over the years, as college sports evolved into a mega-enterprise, lawsuits and labor actions chipped away at that model, which came to be increasingly seen as exploitative in big-money sports like football and men’s basketball.

But the N.C.A.A.’s $2.8 billion settlement on Thursday night in a class-action antitrust lawsuit represents the heaviest blow — and perhaps a decisive one — to that system.

If approved by a U.S. district judge in California, the settlement would allow for the creation of the first revenue-sharing plan for college athletics, a landmark shift in which schools would directly pay their athletes for playing.

This sea change, though, also carries its own questions, according to critics. Those include whether women would be compensated fairly, whether smaller conferences would bear a disproportionate burden of the settlement and whether this framework would do anything to limit the power of collectives — the booster-funded groups that entice players with payments to hopscotch from school to school.

“It’s both a historic and deeply flawed agreement,” said Michael H. LeRoy, a law professor at the University of Illinois. “The idea that schools are paying millions of dollars to the people who are selling the TV contracts and filling the seats — that’s good. But it closes one Pandora’s box and opens four or five others.”

In recent years, college athletes had already made significant strides in gaining the right to make money for their performances. Three years ago, they were allowed for the first time to individually market their name, image and likeness legally. And in March, the men’s basketball team at Dartmouth voted to form a union after a federal official ruled that players were employees of the school. Thursday’s settlement in the case of House v. N.C.A.A. was seen by many college administrators as an inevitable conclusion.