I believe a lot of people, including myself, are hoping for DLCs for Mario Odyssey.
Let's not talk about whether Nintendo would really make DLCs for the game, I just wanna talk about what I wanna see if there really are DLCs.
1. Isle Delfino. A place that quite some people are hoping for.
2. Beanbean Kingdom. I mean, it's also a “Kingdom”, right? It would make a lot of sense to put it in Odyssey.
3. Pill'o Island. Another place from M&L series. Dream Team is actually my favourite game among all the M&L games. Maybe if the place it took place appears in Odyssey, we might be able to see Luigi and go into his dreams to find extra Power Moons! Wouldn't it be cool?
4. Rosalina's comet observatory. There's already a cameo of Rosalina in the game, but we want the real deal. Maybe Mario's Face-ship can be put togeter with it in one map too! Perfect tribute to the galaxy series.
5. Yoshi's Island. Yoshis are a really important species in the Mario series (at least I think so). And it would make more sense to put a Yoshi's inhabitat in the game. Like, we've seen Hopping the bunny in the kingdoms and it's somewhat absurd at the beginning. But later we found more bunnies on the darker side of the moon, and that turned out to be the inhabitat of the bunnies, which would explain where the bunny we chase comes from. I think same thing should go for the yoshi we see in Mushroom Kingdom.
6. Maybe... a place from the Paper Mario series? I dunno. I don't think that's gonna happen tho, but it would be pretty surprising to see it happen, and we know Nintendo is always full of surprises.
7. Crossover! I mean even Sonic Lost world has a Zelda stage and a Yoshi's Island stage as DLCs, right? Can't there be some crossover stages in a main Mario game in DLC form? I truly wanna see Mario in the Hyrule Kingdom collecting purple rupees to buy a Link's outfit.