While society is constantly changing in terms of social and moral acceptability, there are still many things, including homosexuality, that some segments of society deem as morally wrong. As long as that is true, there are always going to be negative consequences for declaring one's identity as a homosexual.

For example, there was a time when when having a child outside of marriage was enough to cause a woman to be ostracized by her family and friends because society did not deem that to be acceptable moral behavior. The same thing often happened with those who chose interracial marriage. Today neither of these things is likely to cause the uproar in society that they once did. The same is true of homosexuality. Though today's society is much more accepting of homosexuality, people who make this public pronouncement still run some risks. 

In school, students risk bullying, teasing, and taunting by classmates and peers, since just being different in a school setting is enough to make them a target.

At home, kids who come out to their families are at risk of losing those valuable relationships. We hear stories all the time about parents, siblings, and extended family members who disown their loved ones because they do not agree with homosexuality. According to the "Homosexuality and Bisexuality" eNotes link (attached below):

[N]early all parents go through a grieving period after learning their child is gay or bisexual. The parents mourn the loss of what they assumes was their child's heterosexuality and "traditional" lifestyle, the lack of grandchildren and their role as potential grandparents, and the improbability of changing their child's sexual orientation.

Of course this is going to have a negative impact on those who reveal their sexual identity to their parents and families. 

Homosexuals who reveal their sexual orientation are also likely to face pressure to change from at least some of the people in their lives, and they are also likely to lose some friends because of it.

Other potential negatives include negative feedback in the workplace and discrimination in other areas of life. While it is not legal to discriminate based on sexual orientation, the reality is that this does happen sometimes.

Realistically, it may not be the actual "coming out" which will cause the most trouble. Young people who do not hide their sexual orientation are more likely to experience problems after the fact. 

Numerous studies show that gay and bisexual youth are at a higher risk of dropping out of school, of being kicked outof their homes, and becoming prostitutes, than their heterosexual peers. They also have a higher incidence of drug, alcohol, and tobacco use. Studies have also shown that gay and bisexual adolescents are two to seven times more likely to commit or attempt suicide compared to heterosexual children and teens. Other studies have found that 45 percent of gay males and 20 percent of lesbians were victims of verbal or physical abuse in middle and high school and were two to four times more likely to be threatened with a weapon compared to heterosexual students.

Clearly there are some potential negative consequences which can occur after people announce their alternative sexual orientation; what seems to be even more difficult and negative is living in an environment which still sees homosexuality as deviant, or at least different.