By the end of the first game, Shulk denounces the role of god and states that he wants a wordl without them. As the camera zooms out, we note that the world no longer has the Bionis and Mechonis, but instead has a wide ocean.
It's interesting to note that the current set-up of the game: 1) has Titans, which effectively serves as landmasses and replace the 'gods' we are familiar with from XC; and 2) takes place in the clouds, whereas the ending of XC decidedly takes place on a more 'normal' geographical arrangement with one landmass and a spread-out ocean.
As others have pointed out in this thread, the setup is quite similar to Baten Kaitos.
I'm wondering: supposing that we are seeing a direct sequel to XC, is the fact that SHulk asked for a world without gods resulting in the fact that there are several 'drivers' in existence in the world of XC2? Certainly, this would mean that Shulk's previous ability to wield the Monado has now become more widely spread across races and individuals. What's interesting, though, is that this has not necessarily removed the need for Titans to serve as floating islands and homes for the races that used to live, presumably, below the cloud sea.
I would imagine that, if there is any direct link, one of Rex's diving expeditions is going to eventually uncover a relic that explains what happened to the world post-the-ending of XC and resulted in the Titans arising and people moving to live above the clouds.
