I think SP's hit the nail on the head, but I do think the expected reaction from the public, in reality, wouldn't be nearly as extreme as some people expect, at least once the initial fuss has died down.
It would take one very brave man to be the first and it makes me wonder whether a group 'outing' of a number of players would be useful. After all, would a group of Liverpool fans, for example, (I'm a Liverpool fan so no preference) tear apart a Norwich player (for example) for being gay if one of our own had recently come out?
A bit rose tinted I appreciate but worth thinking about!