Sky Island biome (In the Over World)

I know that the sky dimension was already turned into the Ender, but what about sky islands in the over world? Caves and Cliffs already focused a lot on exploring further down into the Minecraft over world, however there has not been much focus on upward exploration beyond the mountains. Sky islands could be floating islands only found high up in the sky. They would be part of the over world, but feel like their own dimension (like the Deep Dark). Sky islands could have some unique structures, mobs and items. They could maybe even have a boss. These islands would be accessible by building up from mountains, elytra, or red stone devices. Maybe they could also have some sort of tamale flying mob that could only be tamed with an item from defeating the boss. This would make traveling to more sky islands easier.