We know there are six worlds (plains, desert, forest, snow, jungle, lava), but where do you think the final world will take place? Maybe a galaxy or night theme because of the sticker comet? Do you think there will even be anything past the lava world?
I think it's possible that the final world will take place at Bowser's Castle or a dark world where Bowser resides for the final fight. I hope there is another world after the stated six, because there's usually one more than the number of objects you need to collect.
Here's a random but awesome speculation :
5 worlds to start (Plains, Desert, Forest, Snowy Mountain, Jungle) - can all be completed in any world you want to.
After 5 royal stickers have been found, you go to Bowser's Castle, where Bowser is with the final one. (It's on a Volcano )
After defeating Bowser (Peach was in another castle, as a Toad inside says), you'll get the final royal sticker.
After you get them all, Kersti thanks you and invite you to go to the Sticker Star with her, and Mario accepts.
When they both get there, something strange has happened, and everything's gone crazy up there, and Mario must help Kersti make the area sane. (7th world - boss, IDK... sticker master? (Some leader/ruler of the sticker star gone insane) )
After defeating the boss, making him sane, and return the royal stickers to him, one of the royal stickers will fold into a Goomba and laugh, revealing that Bowser tricked Mario into believing that he defeated Bowser so Bowser could catch him off guard and take him out, but when Mario was almost immediately invited to go to the Sticker Star, Bowser decided it would be smart to tag along. (Don't tell me how a Goomba knows all this stuff )
Then Bowser appears out of nowhere and steals all of the royal crowns and uses them to build a "new" new galactic empire with Peach who he decided to bring along (He then knocks out Mario again to make sure he doesn't interfere ).
With the power of the royal stickers, he creates it really fast, and by the time Mario wakes up, Bowser's new galaxy has been created!
To get to this galaxy, Mario must collect a bunch of things and make them into stickers, so he can use them in a certain way to launch himself to Bowser's Galaxy. Then Mario travels through Bowser's Galaxy, with a lot of forced battles against the previous bosses, as well as one with Bowser Jr. (with a royal sticker) and Kamek. When you defeat all 6 bosses (each one held a royal sticker because Bowser didn't need them anymore), you unlock a final door to Bowser's new awesome battle arena, that works even better than the one in Paper Mario.
After a long climatic fight, Bowser is defeated, Peach is rescued, and they all head out.
...oh, and then the arena blows up, destroying the whole galaxy with it.
The Royal Stickers stop it from becoming a huge problem, though, because they are that powerful.
...that's it. My final worlds on Paper Mario : Sticker Star.
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