This game is fantastic so far, and I love what is being added. I think developing the caving in this game is the next major step. Right now Ill travel forever and never find a cave that goes deep. It leaves me strip mining for resources, and thats not quite as fun as finding them in a cave. I think adding in deepslate and basically making the caves and underground extend twice as far would be amazing.

Adding in ancient cities and/or trial chambers could be done at the same time. But making caves more frequent and have them go deeper would be a major upgrade for caving. I think this is so important because it will be many people's first impression of the game in survival. End game stuff like the End can wait (though that would be amazing in the future).