The first openly gay man in a major American team sport may turn out to be former Middle Tennessee State kicker Alan Gendreau, who hopes to get a shot at the NFL this year. And, if he’s successful, that could translate into millions of dollars in endorsements and speaking engagements, experts say. Whether it’s the Sun Belt Conference’s leading scorer or someone else, the athlete who makes sports history by coming out will likely be sought after by companies that want to appeal to the lesbian, gay, bisexual and transgender population, whose annual buying power last year was estimated at...