I hope i'm right too.
This is what I understand from reading it:
Let's say we go to visit the world of Notre Dame with Sora. Well we play through that world until we get to the point where Frollo captures him, Quasimodo, Asmeralda, and Febes in the court of Miracle. Sora is knocked out by one of Frollo's guards and the screen goes black. The next thing ya know you're suddenly in control of Riku who just arrived in the Jungle Book world. You play as Riku up to a certain point in that world and then after a particular cutscene you'll go back to control Sora in Notre Dame's world and you'll continue where the story with Sora left off, basicaly Sora will be locked up in the bell tower or something with Quasimodo trying to convince him to break free and save Asmeralda. Then you'll finish the story in that world and once you're finished there then control shifts back to Riku and you finish his story in the Jungle Book World.
Now I'm guessing that is what it will be like judging from what I read.