So I suppose a lot of you don't know about this, but let me make it clear for you:
This update will have only 3 new biomes (deep dark, lush caves and dripstone caves) and it will have only one new ore (copper ore), all of this has been already revealed in the minecon 2020 online.
I know it sounds underwhelming, but I was actually thinking that at some point last year, mojang confirmed they already knew the themes for the next 3 updates (1.17, 1.18 and 1.19), which makes me think that it is possible to get cave update 2.0 as 1.18?
Considering it's THE MOST requested update of all time, I wouldn't be surprised if they do another update to the caves adding a few more biomes, mods and generation to give it some justice. Otherwise, it does feel underwhelming if we get only one new, relatively underwhelming ore and just 3 new cave biomes, although I can't complain about the generation. A cave update 2.0 will fix all these issues!