The thought of tailgate-free Sundays and aimless channel surfing might distress diehard National Football League fans, but not everyone stands to suffer should the league’s labor dispute lead to the cancellation of games in the fall.

As owners and players try to stave off a lengthy work stoppage and fans brace for the possible disruption of their long-held Sunday traditions, the sports leagues that for years have been bruised by competition with the powerhouse NFL stand ready to leap onto a vacated stage.

“It does help everyone else,” said Richard C. Powers, a sports marketing professor at the University of Toronto’s Rotman School of Management. “It increases the opportunity for any sports that overlap with the NFL to showcase their products.”

What’s unclear is the extent to which college football , the National Hockey League , NASCAR and other entities whose seasons run through the fall would benefit should there be a significant stretch of NFL-free Sundays and Monday nights for the first time since the 1982 strike, when the season was cut from 16 to nine games.

On Friday, the NFL’s owners and players agreed to extend negotiations on a new collective bargaining agreement by a week .

The NFL’s regular-season ratings generally rival or exceed those of World Series games and often quadruple NASCAR’s race afternoons. With the NFL an imposing giant among U.S. sports, there is no obvious No. 2 to pick up its disoriented fans.

“If football were to go away, I don’t think interest pours into another sport,” said Robert Boland, a professor of sports business who specializes in antitrust law and collective bargaining at New York University. “I think it diffuses rather than splashes. I think it goes in a million places rather than one. That’s why it will be hard for somebody to capitalize on it.”

The boost to NFL competitors will be “mixed” said Rick Horrow, a visiting expert on sports law at Harvard Law School. And “it will be weighed against the malaise that may set in for the general fan, who may become tired in general” of the labor battles between millionaire players and billionaire owners, he said.

Still, experts say, leagues are salivating at the chance to showcase their events outside the enormous shadow of the NFL. Some say baseball’s sagging postseason ratings would likely see the greatest bump, especially if the National Basketball Association’s labor issues also result in a work stoppage. The NBA’s collective bargaining agreement expires this summer.

Ratings for two of the past three World Series (the Giants-Rangers in 2010 and Phillies-Rays in 2008) reached historic lows, about 50 percent below what was typical throughout the 1990s. And because playoff schedules are not yet set, Major League Baseball could target vacant Sunday afternoons for key games.

Others say college football would benefit most, as fans desperate for a fix shift their attention to Saturdays, or opportunistic schools or conferences move their games to Sunday afternoons. During the 1982 strike, the networks aired some Division III contests.

“The importance now shifts to college football,” said Wayne McDonnell, Jr., a former Madison Square Garden executive and sports management professor at New York University. “Nothing is going to replace the NFL, but college football is pretty close . . . I wouldn’t be a bit surprised, if the NFL can’t get its act together, for college football to try to take advantage in a lot of ways.”

College football offers the same game, a similar demographic and the same intense loyalties as the NFL. The question will be whether fans used to kicking back in their recliners on languid Sundays would be willing to shift their routines a day. Officials from the Atlantic Coast, Big East and Southeastern conferences said this week there had been no formal discussion of moving games.

Some said their member schools might be unwilling to play on Sundays even if networks or cable outlets pushed for such moves.

“If the NFL does not play their games, that will create a little void and I suspect the interest in college football will increase,” said Nick Carparelli, the Big East’s senior associate commissioner. “But I do not expect, if there is an NFL work stoppage, that colleges will contemplate moving their games to Sundays. Saturday in the fall is a college football institution . . . a great tradition.”

There also would be major competitive and logistical issues to consider, according to Randy Eaton, Maryland’s senior associate athletic director and chief financial officer.

“You start having to look at the competitive advantages and disadvantages of going Sunday-Saturday, as opposed to Saturday-Saturday with your team,” Eaton said. “There would be some major conundrums that would be had. Last year when we moved the Navy game from Saturday to Monday, Navy just had a nightmare because so many of their fans travel from out of town.”

NASCAR already occupies a Sunday afternoon television slot, and it historically has been blistered in head-to-head competition with the NFL’s regular season. An increase in viewership would be expected; the only question is whether it would be a meaningful boost.

NASCAR has seen its ratings shrink in recent years, and no one doubts its face-offs with the NFL have contributed. In 2004, it created a 10-race playoff and finally was rewarded with a nail-biting finish last year when three drivers were in contention on the last weekend. Yet that Nov. 21 finale earned just a 3.3 rating (5.6 million average viewers) as it went up against Week 11 of the NFL season — which included clashes between New England and Indianapolis, Green Bay and Minnesota, and the Jets and Houston.

Earlier this year, NASCAR officials said they would move start times from 1 p.m. to 2 or 3 to avoid competing directly with NFL games.

“NASCAR has the greatest opportunity for gain,” Powers said. “They lose to the NFL. If the NFL is not there, they control those slots.”

The NHL also could make strides as it seeks to reclaim its stature as one of the nation’s four major sports, while niche sports such as figure skating and downhill skiing might also see occasional prime weekend airtime.

Hockey suffered enormously when it became the first U.S. professional sport to have an entire season wiped out by a work stoppage in 2004-05, and it hasn’t regained its footing. Last year’s television ratings for NBC (eight Games of the Week) and Versus were up from the previous year, but still were small-sport numbers: 0.9 (1.3 million viewers) and 0.4 (365,000).

“The damage [a work stoppage] does to a league’s brand is incalculable,” Powers said. “When there wasn’t any hockey, do you want to know what took up space on sports channels? Poker. I’m serious. That’s what everybody got.”

They also got more college basketball games, which some analysts say has provided a lasting boost to the NCAA tournament.

The Sunday NFL slot is considered so sacred that some speculate that no matter what substitute is provided — whether it’s college football or a figure skating exhibition — some fans will seek out non-sport substitutes or turn off the television rather than tolerate what they would consider second-hand offerings.

“I don’t know that anybody is simply going to double-down on baseball or double-down on NASCAR,” Boland said. “I think some might say, ‘I’m just going to hold on to my money.’ . . . The NFL is the singular cultural marker of America. All of the others compete on a different scale for percentages and pockets.”

Staff writer Steve Yanda contributed to this report.