As anime continues to decline, with its veterans and luminaries moving onto bigger and grander things, other animation industries will take its place. Over time, you’ll have wonderful animated productions for adults based on literary classics like The Divine Comedy and Canterbury Tales. It’s been done through though in here it won’t be so watered down.
Even animated adaptations of stories like Faust and Sorrows of Young Werther would see the light of their day. Though in keep in mind that for every high-minded adaptation, there’s going to be room for less loftier adult animation. Some of which is gross porn and one of them is adapted from the stories of Marquis de Sade.
What’s inevitable is that other animation industries will fill in Japan’s gap if or when anime dies anyways.