I don't think religious establishments would stay away from gay marriage for long. New generation would not have the same feelings about gay marriage as the old generation does. And religious establishments are always looking for new sources of donation, so if hating gays wouldn't sell anymore, why not include them? I don't think this is a "never" issue for church.
Maybe for some of the more "fad" churches but you won't see that in the Catholic, Mormon, more traditional Protestant, or Muslim religions.
