Short term, they could do that, yes. It is theoretically possible. Of course, remember how huge Rick Santorum's campaign was in 2012? Neither do I. The Republican nominee that year was Mitt Romney, a man who has been willing to compromise on social issues with the Democrats in the past.
But a large scale cultural shift is necessary if the anti gay viewpoint is to be a relevant view long term. Even if this decision does get reversed, the homophobes would still be living on borrowed time. Their demographic is crumbling fast. And unlike with racial issues, they have another major weakness. Many of the racial issues facing America, I believe, are caused more by ignorance and isolation than by genuine malice. I promise you that the white residents of my small town are disgusted by the views of the neo Nazis, yes, even the ones who posted on Facebook in support of the police in certain cases. By contrast, homosexuals can be born anywhere. My home town had maybe one or two black people attending the local high school. The fact that anyone, anywhere, can be homosexual means that ignorance will be harder to come by. That is a huge part of why the gay rights movement had such rapid success. Many young people realized that the people who were being accused of causing 9/11 by their foaming at the mouth preacher were their best friends. And with that realization, humanity's moral instinct, the very same instinct that apologists insist points to God, kicked in and told the religious fundamentalism where to shove it.