I think for this one, they should make some different locations.
They haven't really done a BEACH yet, just a jungle. I want a beach like Gelato Beach xD
A WHOLE CHAPTER in Outer Space would be cool, kinda like SPM, but in the traditional Paper Mario style.
Grasslands get old, so how about, as a Chapter 1, do a different dimension where you have to start your journey to find out about the evil source?
Here are my chapter ideas xD (There should be 10)
Chapter 1 - A weird dimension to find a weird source of villains
Chapter 2 - Outer Space to send signals about the weird source.
Chapter 3 - A beach to meet a PIANTA and NOKI who will be partners.
Chapter 4 - The Big City!
Chapter 5 - Rainbow Road xD
Chapter 6 - Bowser's Castle - he is the cause for the source, but the source is now out of his control.
Chapter 7 - Clouds - These strange creatures are great trackers...
Chapter 8 - Under the Sea - those strange creatures sent us here, only to get swallowed by a whale.
Chapter 9 - Factory - The Evil Source is revealed! Defeat his minions here!
Chapter 10 - Ancient Theme - An Ancient World with a volcano. The evil villain is awaiting you, and so is Princess Peach.
BONUS WORLD - Toadette Land! - Release Toadette! The Koopalings have been guarding her here, so she wouldn't be available for 5-6 years. The Koopalings will teleport you to their own world within this bonus chapter. Other than that... it is like a Toad Town with a castle. The plaza will open teleporters to the mini Koopaling worlds. (Bowser jr TOO)