I think a player can benefit from revealing that he's gay. Look at Frank Ocean - before he revealed he's gay he was basically unknown, but after, he became a huge star, his album was released early due to high demand from fans - it went #1 on iTunes, he got invited to lots of shows and music awards. It's expected that he'll be nominated for several Grammys and other musicians praised him for coming out. I think the first one to come out could potentially really benefit from it. Society is more acceptable of gays & lesbians than ever.
That's not exactly true. Frank was well known in hip hop because he was a member of Odd future, and he has some high profile colaborations like Beyonce. It was a good buzz about him and his talent way before Channel Orange was released.
He came out (well that wasn't exactly a coming out) because he was very honest in his lyrics, so anybody who hear the album will know that some of the lyrics talk about men.
The fact that the reviews of the album were great probably help him to have good sales.
I think sooner or later a player will decide to come out, but it has to be because he really feels better doing it. Right now most young talented players are struggling to reach their potential, and coming out (in the case that one of them is gay) will be a big distraction.
And it depends of personality, some mentioned Richard Gasquet, i don't know if he is gay or not, but he is exactly the kind of player who won't come out of the closet, because the guy is very shy and he won't be comfortable aswering questions.
Coming out of the closet is not the same that talking about your private life, saying that you are gay is not giving more information that saying that you are straight, but we know how press works, so the guy who decides to come out must be ready to that.
But the Frank Ocean comparision is good in some sense, a year ago nobody could think that someone linked to hip hop (he is more a r&b singer) will come out, and even less, have success after that. So who knows what is going to happen in a near future. There are rugby players that came out, and in a sports team is far more difficult than in an individual team.
I think the first high profile athlete to come out it will be a tennis player, because is an individual sport (so basically it will be his decision) and because it's a sport well payed. People on individual sports who depends of endorsements are less likely to come out (even with the fact that firms will not retire the endorsements, because that will be very bad publicity), and the same in sport that depends of jury (like gymnastics).