Yeah, seeing as how the game has been confirmed for the XBOX, it would be completely pointless not to release the game to NA shores. Seeing as how the Playstation is how much more popular in Japan, if they weren't going to release the game over seas, then they wouldn't have made it multi-platform.
Actually VERSUS XIII hasn't been confirmed for the 360 yet.
But yeah it would be a bad move for SE not to release it in NA, they would be missing out on a tremendous amount of money, not only is Final Fantasy their leading franchise, but it will also be the first FF to be released on the Next-Gen consoles (along with XIII) and if you look at VII and X which were the first FF's to be released on their respective consoles you will see that both were HUGE financial successes.