I think 20 years down the line, you're going to see the curves of the debate change on issues that we already know are pushing human consciences. I think a lot of the debate between Lincoln and Thaddeus Stevens in this regard: while Lincoln was one of history's greatest abolitionists and basically willed the 13th Amendment into existence, he never believed in extending the franchise to the African-Americans he freed, nor did he believe in extending economic rights and reparations to the slaves who had been freed. Stevens was a radical Republican (a very different thing then than it is now) who believed in both. It took decades for the first idea (political rights for freed slaves) to take hold. The second (economic reparations) have never happened. Lincoln considered Stevens an unrealistic dreamer -- it would take decades for Stevens' ideas to become embraced, and it may take centuries for some of them to be implemented. Yet Stevens thought them at the same time Lincoln decried the ideas as impossible.
Very similarly, there are ideas around the mainstream on issues that are very relevant such as climate change, food preferences, inequality, and sexual preferences that may shift as the Overton window shifts once again. I can't tell if it'll go one way or another. But I do think some of the ideas people deride now, may eventually come to filter into moral discourse (ex: not having children for climate change reasons).