I don't think the coming out itself is going to go away. The stress of it is going to diminish as visible non-heterosexual people will become ever more common-place. But two things, to my mind, will not change anytime soon: 1) The majority of people is and will continue to be (predominantly) straight. So the expectation will continue to be that anyone who doesn't give clear indications otherwise will be assumed straight. 2) Any revelation about people's most private affairs - a big part of which is made up by all things sexual - will continue to be greeted with sensationalist glee, in private circles and the media alike. As long as these two assumptions hold, the phenomenon of the coming out itself will not go away even as the "stigma" continues to fade away.