What is the timeline/ sneak peak on the Dungeon Update?

I’ve been having an urge to play the game again, I mean create a full world urge, but with the dungeon update on the horizon I’m waiting until that is released. So out of curiosity what is the timeline on the dungeon update, and how game changing would it be to implement them into new games?

P.S at the time of writing this I wondered if in the future there could be a possibility of merging zones, so the mountains would be flattened and the zones would be combined together, or flatten the mountain between zones, but the level differences still being there. Tbh I dislike the mountains cutting off the world