Swimming’s international governing body wants to add 10 events to the schedule for the 2020 Olympics in Tokyo. The proposal includes 50-meter races in the butterfly, backstroke and breaststroke; a men’s 800 freestyle; a women’s 1,500 freestyle; and perhaps most intriguing, two mixed-gender relays, a 4×100 freestyle and a 4×100 medley.

FINA proposed the new events last week at the SportAccord Convention in Lausanne, Switzerland, and according to Inside the Games, the organization based its proposal on the schedule that’s been in place since the 2015 world championships, when mixed-gender relays were introduced.

If added to the Olympic program, the new events would likely lead to more medals for the U.S. team. The women’s 1,500, for example, would almost surely give Katie Ledecky another gold medal. Her world record in the event broke the previous one by 13.4 seconds, and she won gold at worlds at that distance in 2013 and 2015.

Having already won a record 28 medals at four Olympics, Michael Phelps likely could have added two more had been able to compete in both the mixed-gender relays. Phelps, now retired, played a major role in the men’s 4×100 freestyle and medley relays in the past four Olympics.

Of course, that’s assuming Phelps would have had time. According to his former coach, Bob Bowman, who also coached the U.S. men’s team at the Rio Games, the International Olympic Committee would have to allow expanded rosters to accommodate an expanded schedule. Without that, he told Swimming World on Monday, “it is highly unlikely” the events will be added.

“I have concerns about adding relay events and also adding individual events while keeping the roster sizes the same,” he said. “The IOC has been insistent on keeping participant numbers at the same level. It doesn’t make sense to add relay events in this dynamic.”

He added that if the IOC is considering extra events for the 2020 program, it would be smart to add only individual events, prioritizing “the men’s 800 and women’s 1,500, then the 50s of strokes, and finally the mixed relays.”

USA Swimming national team Director Frank Busch seconded Bowman’s opinion regarding the two distance races.

“I am sure that the 50s would add a level of excitement to the swimming competition, but swimming is already the most successful sport at the Summer Olympics,” he told Swimming World, adding he’s “not sure why you need to go from an A-plus to A-plus-1.”

Busch said he doesn’t think the mixed relays would move the dial one way or the other.

The IOC might think otherwise, however. The IOC added three mixed-gender events to the past two Olympics, including a mixed sailing event in Rio, and a mixed luge relay and a biathlon event at the 2014 Winter Olympics in Sochi. It’s poised also to add mixed doubles curling to next year’s Winter Olympics in Pyeongchang.

FINA, which also governs other swimming sports on the Olympic program, also proposed adding a mixed-gender synchronized swimming event. Called “mixed duet,” the event was introduced at the 2015 FINA world championships in Kazan, Russia, where American Bill May defeated the usually dominating Eastern European and Asian teams with his partner Christina Jones to bring home a gold medal for their technical program and a silver in their free program.

While synchronized swimming has traditionally been a female-dominated sport — outside of a “Saturday Night Live” sketch by Christopher Guest and Martin Short —  proponents of the event say it is akin to pairs figure skating or ice dancing.

“Seeing two women swim together is a beautiful thing when they are perfectly matched and move like one,” Chris Carver, who coaches May and Jones, told Slate last year. “But the interplay between male and female gives the opportunity for artistry in a whole different dimension.”

The IOC will determine its final list of events for the 2020 Games in July.