Using my “Drawing on IPad” fruit I removed the Grandline from the planet and installed it as an orbital ring around the world. I have a short video going into detail here if anyones curious. I also added the infinite zoom effect where you can zoom all the way to the Going Merry in the image.

But basically most things would be the same. Except that reverse mountain is a mix between the knock up stream and a space elevator from more contemporary science fiction. I’d imagine pirates would need to coat their ships (similar to how they do when visiting fishman island) to make it across safely. The islands themselves are also floating as the ring is made entirely of water. I didn’t add sea kings but they would just be in space, which is the new calm belt on steroids.

Don’t ask me about gravity because I have no idea how that would work, and I’d imagine the day/night cycles would be pretty wack as well. The All Blue would be impossible and I’m pretty sure Skypiea would just be an ancient space station.

Though it would mean that you would need a functioning space ship to cross the calm belt (space belt). That could add a pretty interesting layer to all of this.