I thought this was both interesting and exciting.

As of this point we have seen four kingdoms via the E3 gameplay footage, which are The Metro Kingdom, The Sand Kingdom, The Wooded Kingdom, and The Luncheon Kingdom. While everything I saw suggested this was an awesome game, I was a tiny bit concerned that those four kingdoms didn't look large enough to meet the standards of a 3D Mario game, and there were rumors circulating that the game was indeed limited to those four, with the Metro Kingdom serving as the hub.

Since then, though, the devs have clarified that the Metro Kingdom isn't a hub (and that there's no true "hub" to begin with, saying it was a product of the limits of technology at the time). People then saw on some promotional maps that there was a "Cascade Kingdom" and a "Cap Kingdom", and Nintendo themselves went on to reveal the "Seaside Kingdom".

Well, people have since been scouring all boxart and illustrations that they can find, and on the boxart for amiibo being released in Russia, some savvy fan found "The Mushroom Kingdom", "The Snow Kingdom", and "The Lake Kingdom" all labeled on the box with the others.

So at this point there appears to be at least 10 Kingdoms in the game; as these images are generally obstructed, there might be more that haven't been spotted yet. I think I'm already at maximum hype for this game, but this certainly dispelled the only lingering doubts I had.

Is there anything else you guys hope they spot in the game? The only thing I can think of that would be neat to see is if they show some love to Sarasaland from Super Mario Land; there were many interesting creatures and such in that one that they've never really revisited, and it looks like the Sand Kingdom may be based on it (we've already seen inverted pyramids, the lion, and Moai statues). 

source: https://www.youtube.com/watch?v=fMvwuxKYGmE

Hoping for at least 15 or 20, though that may be pushing it.
The Galaxy games had a shit ton of galaxies.

Me too! I thought since the game was based on a lot of real world locations that they wouldn't put the mushroom kingdom in. 

As of right now it looks like Metro is the only "real world" location, and that's mostly as it's themed after the old Donkey Kong arcade game. The Sand one seems to be themed after Sarasaland from Super Mario Land, so maybe we'll more of that.

If Mario Odyssey is like any other 3D mario game there will be a lot to explore. I am assuming 10 is like the least it can possibly have. My guess is between 15 to 20.

Well, that sounds like quite a bit, so that sounds pretty good..?

One thing I'm hoping for (but don't mind if it's absent) are those little hidden worlds that feature only a couple stars/moons. I absolutely loved finding those in the past, really drove me to search every corner for new things.

I agree, sounds like a lot to me, as far as counts for worlds/themes go in Mario games at least. Should be a fairly big game :) Maybe Nintendo is happy to be getting practice at developing games with generally way more depth these days.

I hope so. I stopped following this game after the reveal, since I've seen enough. It does sound like the dev team were given a good amount of freedom with this game. I can't wait to play it :D

It's typically around ten main ones along with 4-7 subs within them anyway. I wonder how Mushroom Kingdom will actually look though?