Caves and Cliffs: Fixing the world height

The Caves and Cliffs update will bring giant mountains and spacious caves to the over world, making it feel more natural then ever before. 

However with our current 256 height limit, we may not have space to fit all of these features. Unless...we modify them.

Existing Ideas

People have been speculating that Mojang is just going to raise the world height to 512, add a bit more height to the default sea level (y63), and leave the underground for the caves. However, I dont think this is a very good idea. 

If a world were made before 1.17, and then updated to the newest version, It could create massive walls of terrain while the player is exploring. This could make it difficult to find new dungeons and structures.

Caves

I dont think it’s entirely impossible to make blocks spawn below y0. So, we could Make bedrock spawn all the way down at -128, changing the depth of the underground to 180 blocks. Some of the big caves could be 80-120 blocks deep, leaving the deep dark 60-100 blocks below it.

Mountains

The highest parts of mountains right now range from 105 - 110 blocks, leaving 146-149 blocks of air in the sky. So, they should just let mountains generate all the way to y256.

With either of these suggestions, the average height of a mountain could be 193 blocks tall, and the total world height being 384 blocks. However if Mojang is planning to double it to 112, I hope they keep sea level the same, expand the underground to -128, and just add more height for mountains.

Thanks for reading! :)